Method for the preparation of novel sidechain-bearing taxanes and intermediates thereof

ABSTRACT

Methods for the preparation of sidechain-bearing taxanes, comprising the preparation of an oxazoline compound, coupling the oxazoline compound with a taxane having a hydroxyl group directly bonded at C-13 thereof to form an oxazoline sidechain-bearing taxane, and opening the oxazoline ring of the oxazoline sidechain-bearing taxane so formed. Compounds prepared by the methods of the present invention are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/917,158,filed Aug. 25, 1997, now U.S. Pat. No. 6,090,951, which is acontinuation of application Ser. No. 08/600,353, filed Feb. 12, 1996,now abandoned, which is a continuation of application Ser. No.08/171,792, filed Dec. 22, 1993, now abandoned, which is acontinuation-in-part of application Ser. No. 07/995,443, filed Dec. 23,1992, now abandoned, which are hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to methods for the preparation ofsidechain-bearing taxanes and intermediates thereof, and to the novelcompounds prepared by these methods.

BACKGROUND OF THE INVENTION

Taxanes are diterpene compounds which find utility in the pharmaceuticalfield. For example, taxol, a taxane having the structure:

where Ph is phenyl, Ac is acetyl and Bz is benzoyl, has been found to bean effective anticancer agent. Naturally occurring taxanes such as taxolmay be found in plant materials, and have been isolated therefrom. Suchtaxanes may, however, be present in plant materials in relatively smallamounts so that, in the case of taxol, for example, large numbers of theslow-growing yew trees forming a source for the compound may berequired. The art has thus continued to search for synthetic, includingsemi-synthetic routes for the preparation of taxanes such as taxol andanalogs thereof, as well as routes for the preparation of intermediatesused in the preparation of these compounds.

SUMMARY OF THE INVENTION

The present invention provides a novel, overall method for thepreparation of novel sidechain-bearing taxanes, comprising the followingsteps (a) through (e):

(a) preparing an oxazoline compound of the following formula I or a saltthereof:

 where

R¹ is R⁵, R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N—;

R² is R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N—;

R³ and R⁴ are independently R⁵, R⁵—O—C(O)—, or (R⁵)(R⁶)N—C(O)—;

R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, aryl, or heterocyclo; and

R⁷ is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl orheterocyclo;

(b) converting the oxazoline of formula I or salt thereof to anoxazoline of the formula II or a salt thereof:

 where R¹, R³ and R⁴ are as defined above;

(c) coupling the oxazoline of the formula II or salt thereof with ataxane having a hydroxyl group directly bonded to C-13 thereof, or saltthereof, to form an oxazoline sidechain-bearing taxane of the followingformula III or a salt thereof:

 where R¹, R³ and R⁴ are as defined above, and T is a taxane moietypreferably a compound of Formula IX bonded directly through C-13 of saidmoiety;

(d) contacting the oxazoline sidechain-bearing taxane of the formula IIIor salt thereof with an aqueous acid capable of opening the oxazolinering of said compound of the formula III or salt thereof to form asidechain-bearing taxane of the following formula X or salt thereof:

 where R¹, R³, R⁴ and T are as defined above, and the acid salt at theamine group in said formula X is formed by contact with saidring-opening acid; and

(e) contacting said sidechain-bearing taxane of the formula X or saltthereof with a base to form a sidechain-bearing taxane of the followingformula IV or salt thereof:

 where R¹, R³, R⁴ and T are as defined above.

In addition, the present invention provides the individual methods ofeach of steps (a) through (e) which are novel methods, and the novelcompounds of the formulae I, II, III, IV, IX and X and salts andhydrates thereof as described following. Also included are novelprodrugs of these compounds.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described further as follows.

The terms “alkyl” or “alk”, as used herein alone or as part of anothergroup, denote optionally substituted, straight and branched chainsaturated hydrocarbon groups, preferably having 1 to 10 carbons in thenormal chain, most preferably lower alkyl groups. Exemplaryunsubstituted such groups include methyl, ethyl, propyl, isopropyl,n-butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl,4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl, decyl, undecyl,dodecyl and the like. Exemplary substituents may include one or more ofthe following groups: halo, alkoxy, alkylthio, alkenyl, alkynyl, aryl(e.g., to form a benzyl group), cycloalkyl, cycloalkenyl, hydroxy orprotected hydroxy, carboxyl (—COOH), alkyloxycarbonyl, alkylcarbonyloxy,alkylcarbonyl, carbamoyl (NH₂—CO—), substituted carbamoyl ((R⁵)(R⁶)N—CO—where R⁵ or R⁶ are as defined above, except that at least one of R⁵ orR⁶ is not hydrogen), amino (—NH₂), heterocyclo, mono- or dialkylamino,or thiol (—SH).

The terms “lower alk” or “lower alkyl” as used herein, denote suchoptionally substituted groups as described above for alkyl having 1 to 4carbon atoms in the normal chain.

The terms “alkoxy” or “alkylthio” denote an alkyl group as describedabove bonded through an oxygen linkage (—O—) or a sulfur linkage (—S—),respectively. The term “alkyloxycarbonyl”, as used herein, denotes analkoxy group bonded through a carbonyl group. The term “alkylcarbonyl”,as used herein, denotes an alkyl group bonded through a carbonyl group.The term “alkylcarbonyloxy”, as used herein, denotes an alkyl groupbonded through a carbonyl group which is, in turn, bonded through anoxygen linkage. The terms “monoalkylamino” or “dialkylamino” denote anamino group substituted by one or two alkyl groups as described above,respectively.

The term “alkenyl”, as used herein alone or as part of another group,denotes optionally substituted, straight and branched chain hydrocarbongroups containing at least one carbon to carbon double bond in thechain, and preferably having 2 to 10 carbons in the normal chain.Exemplary unsubstituted such groups include ethenyl, propenyl,isobutenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl,decenyl, and the like. Exemplary substituents may include one or more ofthe following groups: halo, alkoxy, alkylthio, alkyl, alkynyl, aryl,cycloalkyl, cycloalkenyl, hydroxy or protected hydroxy, carboxyl(—COOH), alkyloxycarbonyl, alkylcarbonyloxy, alkylcarbonyl, carbamoyl(NH₂—CO—), substituted carbamoyl ((R⁵)(R⁶)N—CO— where R⁵ or R⁶ are asdefined above, except that at least one of R⁵ or R⁶ is not hydrogen),amino (—NH₂), heterocyclo, mono- or dialkylamino, or thiol (—SH).

The term “alkynyl”, as used herein alone or as part of another group,denotes optionally substituted, straight and branched chain hydrocarbongroups containing at least one carbon to carbon triple bond in thechain, and preferably having 2 to 10 carbons in the normal chain.Exemplary unsubstituted such groups include ethynyl, propynyl, butynyl,pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl, and the like.Exemplary substituents may include one or more of the following groups:halo, alkoxy, alkylthio, alkyl, alkenyl, aryl, cycloalkyl, cycloalkenyl,hydroxy or protected hydroxy, carboxyl (—COOH), alkyloxycarbonyl,alkylcarbonyloxy, alkylcarbonyl, carbamoyl (NH₂—CO—), substitutedcarbamoyl ((R⁵)(R⁶)N—CO— where R⁵ or R⁶ are as defined above, exceptthat at least one of R⁵ or R⁶ is not hydrogen), amino (—NH₂),heterocyclo, mono- or dialkylamino, or thiol (—SH).

The term “cycloalkyl”, as used herein alone or as part of another group,denotes optionally substituted, saturated cyclic hydrocarbon ringsystems, preferably containing 1 to 3 rings and 3 to 7 carbons per ring.Exemplary unsubstituted such groups include cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl,cyclododecyl, and adamantyl. Exemplary substituents include one or morealkyl groups as described above, or one or more groups described aboveas alkyl substituents.

The term “cycloalkenyl”, as used herein alone or as part of anothergroup, denotes such optionally substituted groups as described above forcycloalkyl, further containing at least one carbon to carbon double bondforming a partially unsaturated ring.

The terms “ar” or “aryl”, as used herein alone or as part of anothergroup, denote optionally substituted, homocyclic aromatic groups,preferably containing 1 or 2 rings and 6 to 12 ring carbons. Exemplaryunsubstituted such groups include phenyl, biphenyl, and naphthyl.Exemplary substituents include one or more, preferably three or fewer,nitro groups, alkyl groups as described above or groups described aboveas alkyl substituents.

The terms “heterocyclo” or “heterocyclic”, as used herein alone or aspart of another group, denote optionally substituted fully saturated orunsaturated, aromatic or non-aromatic cyclic groups having at least oneheteroatom in at least one ring, preferably monocyclic or bicyclicgroups having 5 or 6 atoms in each ring. The heterocyclo group may, forexample, have 1 or 2 oxygen atoms, 1 or 2 sulfur atoms, and/or 1 to 4nitrogen atoms in the ring. Each heterocyclo group may be bonded throughany carbon or heteroatom of the ring system. Exemplary heterocyclogroups include the following: thienyl, furyl, pyrrolyl, pyridyl,imidazolyl, pyrrolidinyl, piperidinyl, azepinyl, indolyl, isoindolyl,quinolinyl, isoquinolinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl,benzoxadiazolyl, and benzofurazanyl. Exemplary substituents include oneor more alkyl groups as described above or one or more groups describedabove as alkyl substituents. Also included are smaller heterocyclos,such as, epoxides and aziridines.

The terms “halogen”, “halo”, or “hal”, as used herein alone or as partof another group, denote chlorine, bromine, fluorine, and iodine.

The term “taxane moiety”, as used herein, denotes moieties containingthe core structure:

which core structure may be substituted and which may contain ethylenicunsaturation in the ring system thereof.

The term “taxane”, as used herein, denotes compounds containing a taxanemoiety as described above.

The term “hydroxy (or hydroxyl) protecting group”, as used herein,denotes any group capable of protecting a free hydroxyl group which,subsequent to the reaction for which it is employed, may be removedwithout destroying the remainder of the molecule. Such groups, and thesynthesis thereof, may be found in “Protective Groups in OrganicSynthesis” by T. W. Greene, John Wiley and Sons, 1991, or Fieser &Fieser. Exemplary hydroxyl protecting groups include methoxymethyl,1-ethoxyethyl, 1-methoxy-1-methylethyl, benzyloxymethyl,(β-trimethylsilylethoxy)methyl, tetrahydropyranyl,2,2,2-trichloroethoxycarbonyl, t-butyl(diphenyl)silyl, trialkylsilyl,trichloromethoxycarbonyl, and 2,2,2-trichloroethoxymethyl.

The term “salt” includes acidic and/or basic salts formed with inorganicand/or organic acids and bases. Exemplary acidic salts include saltsformed with mineral acids such as HCl, H₂SO₄, or HNO₃, or carboxylicacids such as trifluoroacetic acid or acetic acid. Exemplary basic saltsinclude salts formed with amines such as triethylamine,diisopropylethylamine, or pyridine or amino acids such as arginine, orguanidine. Salts of hydroxyl groups, such as metal (e.g., alkali oralkaline earth metal) alkoxides, are also contemplated as “salts”herein. Metal alkoxide salts may, for example, be formed by contacting ahydroxyl group with a metallating agent.

Reference to a compound employed in or prepared by the methods of thepresent invention includes salts and hydrates thereof, unless otherwiseindicated.

Preparation of Oxazoline Compounds of the Formula I and Salts Thereof

The present invention provides novel methods for the preparation ofoxazoline compounds of the formula I and salts thereof, in particular,the dehydration, displacement, and exchange methods described following.

The present invention also provides the novel oxazoline compounds of theformula I and salts thereof, including all stereoisomers thereof, eithersubstantially free of other stereoisomers, or in admixture with otherselected, or all other stereoisomers, with the provisos that, when R¹ isphenyl and one of R³ or R⁴ is hydrogen, (i) R² is not methoxy when theother of R³ or R⁴ is pentadecyl, benzyl, or methoxycarbonyl, or (ii) R²is not ethoxy when the other of R³ or R⁴ is ethoxycarbonyl; when R¹ ismethyl and one of R³ or R⁴ is hydrogen, R² is not 8-phenylmenthyloxywhen the other of R³ or R⁴ is 2-methylpropyl; and when R¹ isacetylmethyl and R³ and R⁴ are hydrogen, R² is not ethoxy or NH₂.

Oxazolines of the formula Ia and salts thereof described following arepreferred, especially compounds of the formula Ia having thosesubstituents set forth in the section below entitled “PreferredCompounds”.

Dehydration Method

Oxazoline compounds of the formula I or salts thereof may be prepared bya dehydration method, comprising the step of contacting a compound ofthe following formula V or a salt thereof:

where R¹, R², R³ and R⁴ are as defined above, with an acid capable ofeffecting dehydration of the compound of formula V or salt thereof toform a compound of the formula I or salt thereof.

The starting compounds of the formula V and salts thereof may beprepared by procedures such as those described in U.S. patentapplication Ser. No. 07/975,453, filed Nov. 12, 1992 by Patel et al.;Ojima et al., J. Org. Chem., 56, 1681-1683 (1991); Georg et al.,Tetrahedron Lett., 32, 3151-3154 (1991); Denis et al., J. Org. Chem.,51, 46-50 (1986); Corey et al., Tetrahedron Lett., 32, 2857-2860 (1991);Deng et al., J. Org. Chem., 57, 4320-4323 (1992); Ojima et al.,Tetrahedron, 48, 6985-7012 (1992); Commercon et al., Tett. Lett., 33,5185-5188 (1992); Denis et al., J. Org. Chem., 56(24), 6939-6942 (1991)(for example, followed by esterification and treatment with acid); andDenis et al., J. Org. Chem., 55, 1957-1959 (1990), all incorporatedherein by reference.

Any acid capable of effecting dehydration may be employed in thedehydration method of the present invention. Exemplary acids includesulfonic acids such as pyridinium p-toluene sulfonic acid, p-toluenesulfonic acid, camphorsulfonic acid, and methane sulfonic acid,carboxylic acids such as trifluoroacetic acid or acetic acid, or mineralacids such as HCl, H₂SO₄ or HNO₃. Mole ratios of acid: compound offormula V are preferably from about 1:100 to about 1:1.

The reaction is preferably conducted at a temperature of from about 0°C. to about 200° C., and at a pressure of about 1 atm to about 5 atm.The reaction is preferably conducted under an atmosphere of inert gassuch as argon.

Solvents are preferably employed which are inert, organic solvents suchas toluene, tetrahydrofuran, acetonitrile, benzene or xylene. The amountof solvent employed preferably provides a loading of the startingcompound of formula V of about 2.5% by weight, based on the combinedweight of solvent and formula V compound.

The oxazoline ring of the compounds of the formula I is numbered hereinas follows:

With respect to the 4- and 5-position carbon atoms, the oxazolinecompounds of the formula I may exist as four stereoisomers Ia, Ib, Icand Id as follows:

The compounds of the formula V may also exist as four stereoisomers,with respect to the carbon atoms at the corresponding positions. Thesestereoisomers are the following compounds Va, Vb, Vc and Vd:

A desired stereoisomer of the compound of the formula I may, forexample, be prepared by the present dehydration method by employing theappropriate stereoisomer of the starting compound of the formula V.Thus, use of a compound Va will provide a compound Ia, use of a compoundVb will provide a compound Id, use of a compound Vc will provide acompound Ic, and use of a compound Vd will provide a compound Ib. It ispreferred to employ a single stereoisomer of the starting compound V inthe present dehydration method, although stereoisomeric mixtures mayalso be employed. Use of a compound Va to prepare a compound Ia,especially to prepare a compound Ia having those substituents set forthin the section below entitled “Preferred Compounds”, is particularlypreferred.

Displacement Method

Oxazoline compounds of the formula I or salts thereof may also beprepared by a displacement method, comprising the step of contacting acompound of the formula V or salt thereof, in the presence of a base,with an activating agent capable of activating the hydroxyl group of thecompound of the formula V or salt thereof to allow intramoleculardisplacement and formation of a compound of the formula I or saltthereof, with the proviso that, when R¹ is phenyl, and one of R³ or R⁴is hydrogen, (i) R² is not ethoxy when the other of R³ or R⁴ isethoxycarbonyl, or (ii) R² is not methoxy when the other of R³ or R⁴ isbenzyl.

Any compound capable of activating the hydroxyl group of the compound ofthe formula V and effecting intramolecular displacement may be employedas the activating agent in the displacement method of the presentinvention. Exemplary activating agents include sulfonyl halides such asalkyl sulfonyl halides (e.g., methyl sulfonyl chloride), or arylsulfonyl halides (e.g., benzene sulfonyl chloride or p-toluenesulfonylchloride), phosphorus oxychloride (POCl₃), phosphorus pentachloride(PCl₅), or thionyl chloride (SOCl₂). Mole ratios of activating agent:compound of formula V are preferably from about 1:1 to about 2:1.

Activation of the hydroxyl group of a compound of the formula V or saltthereof may produce a novel intermediate compound of the formula VI orsalt thereof:

where R¹, R², R³ and R⁴ are as defined above, and L is a leaving groupsuch as alkyl sulfonyloxy (e.g., methyl sulfonyloxy), aryl sulfonyloxy(e.g., benzene sulfonyloxy or p-toluenesulfonyloxy), chloro, or aphosphorus oxy group (PO₂— or PO—). The present invention provides theaforementioned novel compounds of the formula VI and salts thereof,including all stereoisomers thereof, either substantially free of otherstereoisomers, or in admixture with other selected, or all otherstereoisomers, with the proviso that, when R¹ is phenyl, R² is methoxyand one of R³ or R⁴ is hydrogen and the other benzyl, L is not chloro.

Bases which may be employed include organic bases such as amines (e.g.,pyridine, triethylamine, diisopropylethylamine, lutidine, or1,8-diazabicyclo[5.4.0]undec-7-ene), or lithium hexamethyl disilazide,or inorganic bases such as alkali metal carbonates (e.g., potassiumcarbonate). Mole ratios of base: compound of formula V are preferablygreater than about 2:1.

The reaction is preferably conducted at a temperature of from about −20°C. to about 100° C., particularly 0° C., and at a pressure of about 1atm. The reaction is preferably conducted under an atmosphere of inertgas such as argon.

Solvents are preferably employed which are inert organic solvents suchas chloroform, methylene chloride, toluene, tetrahydrofuran,acetonitrile or, most preferably, which are basic organic solventscapable of functioning both as solvent and as base for the presentmethod such as pyridine, triethylamine, or lutidine. The amount ofsolvent employed preferably provides a loading of the starting compoundof the formula V of about 10% by weight, based on the combined weight ofsolvent and formula V compound.

A desired stereoisomer of the compound of the formula I may, forexample, be prepared by the present displacement method by employing theappropriate stereoisomer of the starting compound of the formula V.Thus, use of a compound Va will provide a compound Ic, use of a compoundVb will provide a compound Ib, use of a compound Vc will provide acompound Ia, and use of a compound Vd will provide a compound Id. It ispreferred to employ a single stereoisomer of the starting compound V inthe present displacement method, although stereoisomeric mixtures mayalso be employed. Use of a compound Vc to form a compound Ia, especiallyto prepare a compound Ia having those substituents set forth in thesection below entitled “Preferred Compounds”, is particularly preferred.

Exchange Method

Oxazoline compounds of the formula I where R¹ is R¹′ as definedfollowing or salts thereof may also be prepared by an exchange method,comprising the step of contacting a compound of the following formulaVII or a salt thereof:

where R², R³ and R⁴ are as defined above, with a compound of thefollowing formula VIII or salt thereof:

where R¹′ and E are independently alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, aryl or heterocyclo;

with the provisos that, when E is ethyl, one of R³ or R⁴ is hydrogen,and (i) R¹′ is phenyl, R² is not methoxy when the other of R³ or R⁴ ismethoxycarbonyl, and R² is not ethoxy when the other of R³ or R⁴ isethoxycarbonyl; and (ii) R¹′ is methyl, R² is not 8-phenylmenthyloxywhen the other of R³ or R⁴ is 2-methylpropyl.

When both starting compounds VII and VIII are simultaneously employed asacid salts at the NH₂ and HN groups, respectively, an amine base, suchas ammonia or an organic amine base, may be employed to form a free NH₂and/or HN group, respectively, to allow the reaction to proceedefficiently. Any amine base capable of forming the free NH₂ and/or HNgroup(s) may be employed therein. Tertiary amine bases such astriethylamine, diisopropylethylamine, lutidine, pyridine or1,8-diazabicyclo[5.4.0]undec-7-ene are preferred. Mole ratios of aminebase: compound of formula VII are preferably from about 1:1 to about10:1.

The starting compounds of the formula VII and salts thereof may beprepared by methods such as those described in U.S. patent applicationSer. No. 07/975,453, filed Nov. 12, 1992 by Patel et al.; Commercon etal., Tetrahedron Lett., 33 (36), 5185-5188 (1992); Corey et al.,Tetrahedron Lett., 32, 2857-2860 (1991); Ojima et al., Tetrahedron, 48,6985-7012 (1992); and Ojima et al., Tetrahedron Lett., 33, 5737-5740(1992), all incorporated herein by reference. The starting compounds ofthe formula VII and salts thereof may be prepared by methods such asthose described in Kimball et al., Org. Synth. Coll. Vol. 11, p. 284(1943). Use of acidic salts of compounds of the formula VIII, forexample. salts formed with carboxylic, sulfonic or mineral acids, arepreferably employed as starting materials, as such compounds arerelatively stable and easily handled. The aforementioned salts may beneutralized upon contact with the base employed as discussed above. Moleratios of compound of formula VIII: compound of formula VII arepreferably from about 1:1 to about 2:1.

The reaction is preferably conducted at a temperature of from about 0°C. to about 100° C., and at a pressure of about 1 atm. The reaction ispreferably conducted under an inert atmosphere, such as argon ornitrogen.

Solvents are preferably employed which are inert organic solvents suchas toluene, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, orchloroform. The amount of solvent employed preferably provides a loadingof the starting compound of the formula VII of about 6% by weight, basedon the combined weight of solvent and formula VII compound.

The compounds of the formula VII may, as with the compounds of theformula V, exist as four stereoisomers with respect to the carbon atomsat the corresponding positions. These stereoisomers are the followingcompounds VIIa, VIIb, VIIc and VIId:

A desired stereoisomer of the compound of the formula I may, forexample, be prepared by the present exchange method by employing theappropriate stereoisomer of the starting compound of the formula VII.Thus, use of a compound VIIa will provide a compound Ia, use of acompound VIIb will provide a compound Id, use of a compound VIIc willprovide a compound Ic, and use of a compound VIId will provide acompound Ib. It is preferred to employ a single stereoisomer of thestarting compound VII in the present exchange method, althoughstereoisomeric mixtures may also be employed. Use of a compound VIIa toprepare a compound Ia, especially to prepare a compound Ia having thosesubstituents set forth in the section below entitled “PreferredCompounds”, is particularly preferred.

Preparation of Oxazoline Compounds of the Formula II and Salts Thereof

Oxazoline compounds of the formula II and salts thereof may be preparedfrom oxazoline compounds of the formula I and salts thereof byconverting the group —C(O)—R² to the group —C(O)—OH.

Any agent capable of the aforementioned conversion may be employed. Forexample, when R² is alkoxy such as methoxy or ethoxy, the compound ofthe formula I or salt thereof may be dealkylated to form a compound ofthe formula II by use of a suitable nucleophilic agent, such as thealkali or alkaline earth metal salts of methanethiol. Alternatively,hydrogenation may be employed, for example, to convert groups such asbenzyloxycarbonyl to carboxyl, by use of a hydrogenating agent, forexample, hydrogen and a hydrogenation catalyst such as palladium.

Preferably, conversion of the group —C(O)—R² to a carboxyl group isconducted by hydrolysis. Any compound capable of effecting hydrolysismay be employed as the hydrolysis agent therein. Exemplary hydrolysisagents include aqueous bases such as hydroxides (e.g., metal hydroxidessuch as barium hydroxide, or preferably, alkali metal hydroxides such aslithium, sodium or potassium hydroxide). Mole ratios of base: compoundof formula I are preferably from about 1:1 to about 3:1. Mole ratios ofwater: compound of formula I are preferably from about 1:1 to about100:1.

The reaction is preferably conducted at a temperature of from about −20°C. to about 100° C., and at a pressure of about 1 atm. Hydroxidesaponification of compounds of the formula I or salts thereof where R²is —N(R⁵)(R⁶) is preferably conducted at the higher temperatures of theaforementioned temperature range, or at temperatures approaching or atthe reflux temperature of the liquid medium employed. The reaction ispreferably conducted under an atmosphere of nitrogen, argon or air.

Solvents may be selected from inorganic and organic liquids such aswater, alcohols, toluene, tetrahydrofuran, dioxane, acetonitrile, ordimethylformamide, or mixtures thereof. A mixture of water and anorganic liquid such as tetrahydrofuran is preferably employed assolvent. The amount of solvent employed preferably provides a loading ofthe starting compound of the formula I of about 7% by weight, based onthe combined weight of solvent and formula I compound.

The present invention also provides the novel compounds of the formulaII and salts thereof, including all stereoisomers thereof, eithersubstantially free of other stereoisomers, or in admixture with otherselected, or all other stereoisomers, with the proviso that, when R¹ isphenyl and one of R³ or R⁴ is hydrogen, the other of R³ or R⁴ is notCOOH. As with the oxazolines of the formula I, the oxazolines of theformula II may exist as four stereoisomers with respect to the 4- and5-position carbon atoms. These stereoisomers are the following compoundsIIa, IIb, IIc and IId:

Oxazolines of the formula IIa and salts thereof are preferred,especially compounds of the formula IIa having those substituents setforth in the section below entitled “Preferred Compounds”.

The stereoconfiguration of the starting compound of the formula I orsalt thereof may be retained and/or inverted in the present method.Thus, for example, hydrolysis of a compound of the formula I havingsubstituents which are in the cis position relative to each other at the4- and 5-positions may be hydrolyzed to provide a compound of theformula II having the corresponding cis configuration, a compound of theformula II having the corresponding trans configuration where the5-position carboxyl substituent is inverted relative to the startingcompound, or a mixture of the aforementioned cis and trans compounds.Bases which, when employed for hydrolysis, deprotonate the carbon atomthrough which the group —C(O)—R² is bonded, and which subsequentlyreprotonate the aforementioned carbon from the opposite face of the ringsystem, result in inversion of the stereoconfiguration. Exemplary suchbases include those described above or alkali metal carbonates such aspotassium carbonate, amine bases, or metal, such as alkali or alkalineearth metal, alkoxides, the latter which may be formed prior to additionthereof or in situ (for example, by addition of a metallating agent suchas n-butyllithium together with an alkanol such as ethanol).

Where the stereoconfiguration is inverted during the present method asdescribed above, a compound of the formula I having an invertedstereoconfiguration relative to the starting compound of the formula Imay be formed as an intermediate (i.e., epimerization). Thus, forexample, where the starting compound of the formula I has substituentsat the 4- and 5-positions which are in the cis position relative to eachother, the corresponding trans compound of the formula I where the5-position substituent —C(O)—R² is inverted relative to the startingcompound may be formed as in intermediate during the hydrolysisreaction. The aforementioned inversion method is also contemplatedwithin the scope of the present invention.

Coupling to Prepare Oxazoline Sidechain-bearing Taxanes of the FormulaIII and Salts Thereof

A sidechain-bearing taxane of the formula III or a salt thereof may beprepared by a method comprising the step of contacting an oxazolinecompound of the formula II or a salt thereof, with a taxane having ahydroxyl group directly bonded to C-13 thereof, or a salt thereof, inthe presence of a coupling agent. It is preferred to employ oxazolinesof the formula IIa or salts thereof in the present method, especiallycompounds of the formula IIa having those substituents set forth in thesection below entitled “Preferred Compounds”.

Taxanes are compounds containing the core structure:

which core structure may be substituted and which may contain ethylenicunsaturation in the ring system thereof, as described above. Any taxanecontaining a hydroxyl group directly bonded to C-13 thereof, or saltthereof (such as a metal alkoxide salt at the C-13 hydroxyl group) maybe employed in the present method. The taxane starting material employedin the method of the present invention may be a compound such as thosedescribed in European Patent Publication No. 400,971, incorporatedherein by reference, or may be a compound containing a taxane moietydescribed in, and prepared by procedures described in or analogous tothose set forth in, U.S. patent application Ser. No. 07/907,261, filedJul. 1, 1992 by Chen et al., or in U.S. patent application Ser. No.07/981,151, filed Nov. 24, 1992 by Ueda et al., both incorporated hereinby reference. Exemplary such taxanes include those of the followingformula IX:

where

R⁸ is hydrogen, hydroxyl, R¹⁴—O—, R¹⁵—C(O)—O—, or R¹⁵—O—C(O)—O—;

R⁹ is hydrogen, hydroxyl, fluoro, R¹⁴—O—, R¹⁵—C(O)—O— or R¹⁵—O—C(O)—O—;

R¹⁰ and R¹¹ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, R16—O—, aryl, or heterocyclo;

R¹⁴ is a hydroxyl protecting group; and

R¹⁵ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, arylor heterocyclo,

R¹⁶ is alkyl

or salts thereof.

All stereoconfigurations of the unspecified chiral centers of thecompound of the formula IX are contemplated for use in the couplingmethod of the present invention. The use of a single stereoisomer ispreferred, although mixtures thereof may be employed. 7-Trialkylsilylbaccatin III compounds are one of the compounds preferably employed asthe starting material of formula IX, most preferably, 7-trimethylsilylbaccatin III or 7-triethylsilyl baccatin III.

Another series of compounds which are preferable starting materials offormula IX are compounds wherein R⁸ is OC(O)CH₃; R⁹ is hydroxyl or ahydroxyl protecting group e.g. O-trimethylsilyl or O-triethylsilyl; R¹⁰is as above except methyl and R¹¹ is aryl e.g. benzyl. The lattercompounds are considered novel along with methods for their preparationwhich are set forth below. Especially preferred of the above compoundsare those wherein R¹⁰ is cycloalkyl or OR¹⁶.

The above compounds are prepared by the following general reactionscheme

Step F

Baccatin III is protected at the C-7 and C-13 sites by reaction with asuitable agent, such as, a halotrialkylsilane e.g. trimethyl ortriethyl, 2,2,2-trichloroethyl chloroformate or carbobenzyloxy. Anyinert organic solvent wherein Baccatin III is soluble may be utilized,such as, THF, DMF, MeCl₂ and dioxane. The reaction is carried out in thepresence of a tertiary amine base, such as, pyridine or imidazole. Thereaction temperature can vary from −30° C. to room temperature with C-7substitution occuring preferably at −30° C. to 0° C. and C-13 at 0° C.to room temperature. The protecting group reactant concentration ispreferably in molar excess (1-10) to effect both C-7 and C-13substitution.

Step G

The intermediate XI is thereafter protected at the C-1 hydroxy byreaction with a trimethylsilane or preferably a dimethylsilane e.g.chlorotrimethylsilane or preferably chlorodimethylsilane in, forexample, DMF, THF, dioxane or various ethers. As in step F the reactionis preferably carried out in the presence of a tertiary amine base, suchas imidazole or pyridine. The temperature can range from −30° C. to roomtemperature with about 0° C. as preferred.

Step H

(A) Intermediate XII is thereafter reduced at C-4 to hydroxy by reactionwith a suitable reducing agent such as Red-Al or lithium aluminumhydride. The reducing agent is usually present in molar excess (1-5equivalents). The reaction solvent can be THF, dioxane or varioussuitable ethers and the reaction temperature can range from −30° C. to0° C. with about 0° C. as preferred.

(B) Intermediate XIII of (A) wherein C-4 is hydroxy is converted to theappropriate C-4 substituent by reaction with the appropriate acylchloride acid anhydride or mixed anhydride e.g. acryloyl chloride,benzoyl chloride, cycloalkylcarbonyl chloride, alkyl chloroformate, inthe presence of an alkali metal (Li, Na or K) anion of a secondary aminebase. The reaction solvents include THF, dioxane, etc. The temperaturerange can be from −30° C. to room temperature with about 0° C. aspreferred.

Step I

(A) The intermediate XIII of step H (B) is thereafter deprotected byreaction with pyridinium fluoride (aqueous hydrogen fluoride inpyridine) in acetonitrile followed by tetrabutylammonium fluoride in THFor cesium fluoride in THF. Thereafter the mixture is diluted in analcohol, washed with mild organic or inorganic acid and isolated.

(B) Thereafter the C-7 hydroxy protecting group may be introduced in XIVas in Step F following reaction parameters favoring C-7 substitutionabove.

Subsequently, the appropriate side chain may be introduced at C-13following the novel process disclosed herein or alternatively via Holtonmethodology as disclosed in U.S. Pat. Nos. 5,227,400, 5,175,315 and5,229,526 which are herein incorporated by reference.

As novel end products of the present invention therefore are compoundsof the formula

where

R¹ is R⁵, R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N—;

R³ and R⁴ are independently R⁵, R⁵—O—C(O)—, or (R⁵)(R⁶)N—C(O)—;

R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, aryl or heterocyclo; and

R⁷ is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl orheterocyclo;

and T is

 where

R⁸ is hydrogen, hydroxyl, R¹⁴—O—, R¹⁵—C—(O)—O—, or R¹⁵—O—C (O)O—;

R⁹ is hydrogen, hydroxyl, fluoro, R¹⁴—O—, R¹⁵—C(O)—O— or R¹⁵—O—C(O)—O—;

R¹⁰ and R¹¹ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, R¹⁶—O-aryl, or heterocyclo;

R¹⁴ is a hydroxyl protecting group; and

R¹⁵ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, arylor heterocyclo,

R¹⁶ is alkyl with the proviso that R¹⁰ is not methyl

or salts or hydrates thereof.

Preferred Compounds

Especially preferred among the novel compounds of formula IV are thosecompounds wherein R¹⁰ is cycloalkyl or OR¹⁶. Most preferred among thenovel compound of formula IV are compounds wherein R¹⁰ is cycloalkyl, R¹is aryl, preferably phenyl, or alkoxy preferably t-butyloxy; R³ is aryl,preferably phenyl, heterocyclo preferably 2- or 3-furanyl or thienyl,isobutenyl, 2-propenyl, isopropyl or (CH₃)₂CH—; R⁴ is hydrogen; R⁸ ispreferably hydroxyl or alkylcarbonyloxy, e.g. acetyloxy; R⁹ is hydroxyand R¹¹ is aryl, preferably phenyl.

Any compound capable of effecting esterification of the C-13 hydroxylgroup, or salt thereof, of the starting taxane through the carboxylgroup of the oxazoline of the formula II or salt thereof may be employedas the coupling agent of the present method. Exemplary coupling agentsinclude those compounds forming an activated oxazoline ester (forexample, 1-hydroxybenzotriazole or N-hydroxysuccinimide) or anhydride(for example, an acid chloride such as pivaloyl chloride orbis(2-oxo-3-oxazolidinyl)-phosphinic chloride) when contacted with theoxazoline of the formula II, particularly coupling agents comprising acompound such as a carbodiimide (e.g., dicyclohexylcarbodiimide (DCC),1,3-diisopropylcarbodiimide (DIC), or1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride),bis(2-oxo-3-oxazolidinyl)phosphinic chloride), carbonyl diimidazole(CDI), pivaloyl chloride, or 2,4,6-trichlorobenzoyl chloride; whereinthe aforementioned compounds are preferably employed together with acompound such as 1-hydroxybenzotriazole (HOBt) or N-hydroxysuccinimide(HO—Su), or an amine such as triethylamine, pyridine or pyridinesubstituted at the 4-position with —N(R¹⁶)(R¹⁷), where R¹⁶ and R¹⁷ areindependently selected from alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl or heterocyclo (to form a compound such as4-dimethylaminopyridine (DMAP)), or where R¹⁶ and R¹⁷, together with thenitrogen atom to which they are bonded, form a heterocyclo group (toform a compound such as 4-morpholinopyridine or 4-pyrrolidinopyridine).Mole ratios of coupling agent: starting taxane are preferably from about1:1 to about 2:1. Mole ratios of oxazoline of the formula II: startingtaxane are preferably from about 1:1 to about 2:1.

The reaction is preferably conducted at a temperature of from about 0°C. to about 140° C., and at a pressure of about 1 atm. The reaction ispreferably conducted under an atmosphere of inert gas such as argon.

Solvents are preferably employed which are inert organic liquids such astoluene, acetonitrile, 1,2-dichloroethane, chloroform, tetrahydrofuran,pyridine, methylene chloride or dimethylformamide. The amount of solventemployed preferably provides a loading of the starting taxane of about20% by weight, based on the combined weight of solvent and taxanecompound.

The stereoconfiguration of the substituents at the 4- and 5-positions ofthe starting oxazoline may be retained and/or inverted in the coupledformula III product, for example, epimerization from cis to trans wherethe 5-position substituent has been inverted relative to the startingmaterial is contemplated.

The present invention also provides the novel oxazolinesidechain-bearing taxanes of the formula III and salts thereof,including all stereoisomers thereof, either substantially free of otherstereoisomers, or in admixture with other selected, or all otherstereoisomers.

Ring Opening to Form Taxanes of the Formula X and Salts Thereof

A sidechain-bearing taxane of the formula X or a salt thereof may beprepared from an oxazoline sidechain-bearing taxane of the formula IIIor a salt thereof, by a method comprising the step of contacting ataxane of the formula III or salt thereof with an aqueous acid capableof opening the ring of the oxazoline group bonded through C-13 of thetaxane moiety of said taxane compound to form said compound of theformula X or salt thereof.

Any aqueous acid capable of effecting the aforementioned ring openingmay be employed in the method of the present invention. Exemplary ringopening acids include carboxylic acids, such as acetic acid ortrifluoroacetic acid, or preferably, mineral acids such as hydrochloricacid, hydrofluoric acid or sulfuric acid, in water. Mole ratios of ringopening acid: compound of formula III are preferably from about 1:1 toabout 10:1. Mole ratios of water: compound of formula III are preferablyfrom about 1:1 to about 100:1.

The ring opening reaction is preferably conducted at a temperature offrom about −20° C. to about 40° C., and at a pressure of about 1 atm.The reaction is preferably conducted under an atmosphere of nitrogen,argon or air.

Solvents are preferably employed which are inert organic liquids aloneor in admixture with water such as tetrahydrofuran, alcohols(preferably, lower alkanols such as methanol), dioxane, toluene,acetonitrile, or mixtures thereof. The amount of solvent employedpreferably provides a loading of the starting compound of the formulaIII of about 5% by weight, based on the combined weight of solvent andformula III compound.

A preferred embodiment of the present invention further comprises thestep of deprotecting one or more groups, particularly to free hydroxylgroups, on the taxane moiety to prepare taxanes of the formula X.Deprotection may, for example, be conducted prior or subsequent to, orsimultaneously with, the aforementioned ring opening method by use of adeprotection agent. Any compound capable of deprotection may be employedas the deprotection agent. For example, acids such as hydrofluoric acidor aqueous protic acids, or tetra-alkylammonium fluorides such astetra-n-butylammonium fluoride, may be employed for removal of silylprotecting groups; benzyl protecting groups may be removed byhydrogenation; trichloroethoxycarbonyl protecting groups may be removedby contact with zinc; and acetal or ketal protecting groups may beremoved by the use of protic acids or Lewis acids.

A preferred embodiment of the present invention comprises simultaneousring opening and deprotection of one or more hydroxyl groups on thetaxane ring structure, particularly at C-7. A particularly preferredembodiment comprises the step of simultaneous ring opening anddeprotection by use of an acid (e.g., a mineral acid such ashydrochloric acid) capable of effecting both reactions. Thus, forexample, use of an acid under reaction conditions described above forring opening may allow simultaneous ring opening and deprotection ofacid cleavable hydroxyl protecting groups at C-7 such as trialkylsilyl(e.g. trimethylsilyl or triethylsilyl).

The present invention also provides the novel intermediates of theformula X and salts thereof formed during ring opening and, optionally,deprotection, including all stereoisomers thereof, either substantiallyfree of other stereoisomers, or in admixture with other selected, or allother stereoisomers.

Contact with Base to Form Taxanes of the Formula IV and Salts Thereof

Treatment of a compound of the formula X or salt thereof with a baseprovides a compound of the formula IV or salt thereof. Any base allowingmigration of the acyl group —C(O)—R¹ to the amine group —NH₂, therebyeffecting formation of a compound of the formula IV or salt thereof, maybe employed in the method of the present invention. Exemplary basesinclude alkali metal bicarbonates such as sodium bicarbonate orpotassium bicarbonate. Mole ratios of base: compound of formula X arepreferably from about 1:1 to about 5:1.

The reaction is preferably conducted at a temperature of from about −20°C. to about 80° C., and at a pressure of 1 atm. The reaction ispreferably conducted under an atmosphere of argon, nitrogen or air.

Solvents are preferably employed which are inert organic liquids aloneor in admixture with water such as tetrahydrofuran, alcohols(preferably, lower alkanols such as methanol), toluene, acetonitrile,dioxane, or mixtures thereof. The amount of solvent employed preferablyprovides a loading of the compound of the formula X of from about 1 toabout 5% by weight, based on the combined weight of solvent and formulaX compound.

Deprotection of protected groups may be conducted simultaneously with,or subsequent to use of a base, although deprotection prior to contactwith a base, especially simultaneously with ring opening, is preferablyemployed, as described above.

Separation

The products of the methods of the present invention may be isolated andpurified, for example, by methods such as extraction, distillation,crystallization, and column chromatography.

Sidechain-bearing Taxane Products

The sidechain-bearing taxanes of the formula IV and salts thereofprepared by the methods of the present invention are themselvespharmacologically active. or are compounds which may be converted topharmacologically active products. Pharmaco-logically active taxanessuch as taxol may be used as antitumor agents to treat patientssuffering from cancers such as breast, ovarian, colon or lung cancers,melanoma or leukemia. The utility of such sidechain-bearing taxanes hasbeen described, for example, in European Patent Publication No. 400,971,U.S. Pat. Nos. 4,876,399, 4,857,653, 4,814,470, 4,924,012,4,924,011,U.S. patent application Ser. No. 07/907,261, filed Jul. 1,1992 by Chen et al., and U.S. patent application Ser. No. 07/981,151,filed Nov. 24, 1992 by Ueda et al., all incorporated herein byreference.

Taxotere, having the structure shown following, or especially taxol,having the structure shown above, are preferably ultimately prepared asthe sidechain-bearing taxanes of the formula IV:

Solvates, such as hydrates, of reactants or products may be employed orprepared as appropriate in any of the methods of the present invention.

Also considered within the ambit of the present invention are the watersoluble prodrug forms of the compounds of formula IV. Such prodrug formsof the compounds of formula IV are produced by introducing at C-7 orC-10 and/or at the 2′-position of the side chain a phosphonoxy group ofthe general formula

—OCH₂(OCH₂)_(m)OP(O)(OH)₂

wherein m is 0 or an integer from 1 to 6 inclusive.

The novel prodrugs have the formula

where

R¹ is R⁵, R⁷—O—, R⁷—S—, or (R⁵) (R⁶)N—;

R³ and R⁴ are independently R⁵, R⁵—O—C(O)—, or (R⁵)(R⁶)N—C(O)—;

R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, aryl or heterocyclo; and

R⁷ is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl orheterocyclo;

and T is

 where

R⁸ is hydrogen, hydroxyl, R¹⁴—O—, R¹⁵—C(O)—O—, R¹⁵—O—C(O)—O—, or—OCH₂(OCH₂)_(m)OP(O)(OH)₂;

R¹⁰ and R¹¹ are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, R¹⁶—O—, aryl or heterocyclo;

R²⁰ is hydrogen, —OCH₂(OCH₂)_(m)OP(O)(OH)₂, —OC(O)R²¹ or —OC(O)OR²¹wherein R²¹ is C₁-C₆ alkyl optionally substituted with one to sixhalogen atoms, C₃-C₆ cycloalkyl, C₂-C₆ alkenyl or a radical of theformula

 wherein D is a bond or C₁-C₆ alkyl and R^(a), R^(b) and R^(c) areindependently hydrogen, amino, C₁-C₆ mono- or di-alkylamino, halogen,C₁-C₆ alkyl or C₁-C₆ alkoxy;

R¹⁴ is a hydroxy protecting group;

R¹⁶ is alkyl;

R³⁰ is hydrogen, hydroxy, fluoro, —OCH₂(OCH₂)_(m)OP(O)(OH)₂ or—OC(O)OR²¹ wherein R²¹ is as above.

R¹⁵ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, arylor heterocyclo;

m is 0 or an integer from 1 to 6 inclusive with the proviso that atleast one of R⁸, R²⁰ and R³⁰ is —OCH₂(OCH₂)_(m)OP(O)(OH)₂ and R¹⁰ is notmethyl

and phosphonxy group base salts thereof.

Preferred compounds of formula IV′ include those wherein R¹⁰ iscycloalkyl or OME or OEt; R¹ is aryl, preferably phenyl or alkoxypreferably t-butyloxy; R³ is aryl preferably phenyl or heterocyclo,preferably furyl or thienyl or alkenyl preferably propenyl orisobutenyl; R⁴ is hydrogen; R⁸ is hydroxy or alkylcarbonyloxy,preferably acetyloxy; R¹¹ is aryl preferably phenyl; R²⁰ is—OCH₂(OCH₂)_(m)OP(O)(OH)₂ or —OC(O)OR²¹ wherein R²¹ is ethyl orN-propyl; R³⁰ is —OCH₂(OCH₂)_(m)OP(O)(OH)₂ and m is 0 or 1.

The phosphonoxy group is normally introduced following synthesis of theend products of formula IV following procedures set forth in U.S. Ser.No. 08/108,015 filed Aug. 17, 1993 which is incorporated by referenceherein.

In arriving at the novel prodrugs above, various novel intermediates areformed following the reaction conditions set forth generally in U.S.Ser. No. 08/108,015. Compounds of formula IV are used as startingmaterials wherein non-desired hydroxy groups have been blocked. Theappropriately protected compound of formula IV wherein reactive hydroxygroups are present either at the 2′ or 7 or 10 positions or at multiplepositions is first connected to a corresponding methylthiomethyl ether[—OCH₂(OCH₂)_(m)SCH₃]. Thereafter depending on the value of m, the ethermay be connected to a protected phosphonooxymethyl ether by a variety ofsteps as set forth in the above U.S. Ser. No. The phosphono protectinggroup(s) and the hydroxy protecting groups may thereafter be removed byconventional techniques.

The free acid can then be converted to the desired base salt thereafterby conventional techniques involving contacting the free acid with ametal base or with an amine. Suitable metal bases include hydroxides,carbonates and bicarbonates of sodium, potassium, lithium, calcium,barium, magnesium, zinc, and aluminum; and suitable amines includetriethylamine, ammonia, lysine, arginine, N-methylglucamine,ethanolamine, procaine, benzathine, dibenzylamine, tromethamine (TRIS),chloroprocaine, choline, diethanolamine, triethanolamine and the like.The base salts may be further purified by chromatography followed bylyophilization or crystallization.

The prodrugs may be administered either orally or parenterally followingthe teaching of the above patent application (08/108,015). The compoundsof Formula IV and IV′ are novel antitumor agents showing in vitrocytotoxicity activity against human colon carcinoma cell lines HCT-116and HCT-116/VM46and M109lung carcinoma.

The present invention is further described by the following exampleswhich are illustrative only, and are in no way intended to limit thescope of the instant claims.

EXAMPLE 1 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethylester

(2R,3S)-N-benzoyl-3-phenylisoserine ethyl ester (0.104 g, 0.332 mmoles)was added to an oven-dried 10 ml flask, purged with argon, and suspendedin toluene (5.0 ml). Pyridinium p-toluene sulfonic acid (PPTS) (42 mg,0.167 mmoles) was added. After stirring at room temperature for about 1hour, the mixture was heated to reflux. A clear homogeneous solution wasobtained upon heating. After about 1 hour of heating, the reactionmixture became cloudy. TLC after 16.5 hours of heating showed that thereaction was complete (1:1 ethyl acetate (EtOAc):hexane, PMA(phosphomolybdic acid)/ethanol, ultraviolet (U.V.)).

The reaction mixture was diluted with 10 ml of chloroform, washed with 5ml of saturated aqueous NaHCO₃, dried over Na₂SO₄, filtered, andconcentrated to give 97.8 mg of a yellowish oil (yield=100%). ¹H NMRshowed that the trans-oxazoline title product had been obtained withonly minor (<<5%) impurities, none of which were the correspondingcis-oxazoline.

EXAMPLE 2 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethylester

(2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester (0.100 g, 0.319 mmoles)was added to a flame-dried, argon-purged, 5 ml flask, dissolved inpyridine (1.0 ml), and cooled to 0° C. Methyl sulfonyl chloride (38 mg,0.335 mmoles) was added dropwise, and the yellowish solution was stirredat 0° C. for 1¾ hours, and then warmed to room temperature. Thin layerchromatography (TLC) after 1½ hours at room temperature showed thereaction to be complete (1:1 ethyl acetate:hexane, PMA/ethanol, U.V.).

The heterogeneous mixture was diluted with 5 ml ethyl acetate and washedwith ⅓ saturated aqueous CUSO₄ (10 ml). The aqueous fraction wasextracted with 2×5 ml ethyl acetate. The combined organic fractions werewashed with 5 ml saturated aqueous NaCl, dried over Na₂SO₄, filtered,and concentrated to yield 0.12 g of a yellowish oil.

The title product was purified by silica gel chromatography (column: 20mm d×50 mm l) with 1:1 ethyl acetate:hexane to give 92.6 mg of ayellowish oil (yield=98.3%). ¹H NMR and mass spec. showed that thetrans-oxazoline title product was obtained. Specific rotations: (c=0.1,CHCl₃), [α]_(D)=+15.6°, [α]₅₇₈=+16.3°, [α]₅₄₆=+18.7°, [α]₄₃₆=+33.1°.

The starting compound (2S,3S)-N-benzoyl-3-phenylisoserine ethyl esterwas prepared in a separate experiment as follows:

In a 500 ml flask containing a solution of(4S-cis)-4,5-dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethyl ester(0.79 g, 2.67 mmol) in methanol (MeOH) (57 ml) at 0° C. was added 1N HCl(57 ml) with stirring over a 10 minute period. A precipitate was formedduring the HCl addition which dissolved during the addition oftetrahydrofuran (THF). THF (57 ml) was then added to clear the solution,and the resulting mixture was stirred at 0° C. for 2 hours and 15minutes. The pH of the solution was adjusted to 9.0 with saturatedNaHCO₃ (120 ml) and then the mixture was allowed to stir at roomtemperature for 18 hours. (The reaction was monitored by TLC (silicagel) using 4:6 EtOAc:Hexane as eluent, R_(f) for the startingmaterial=0.71, R_(f) for the product=0.42, UV visualization).

The reaction was diluted with EtOAc (200 ml) and the aqueous layer wasseparated and extracted with EtOAc (100 ml×1). The combined EtOAcsolution was then washed with brine (150 ml×1), dried over Na₂SO₄,filtered and concentrated to give crude(2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester as a solid (0.810 g). Itwas dissolved in hot MeOH (15 ml) and set aside at room temperature for30 minutes and then at 4° C. for 1 hour. The solid was filtered, washedwith cold MeOH (2 ml) and dried in vacuo to give 0.43 g of(2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester as the first crop. Asecond crop (0.24 g) was also obtained as above to give a total of 0.67g (80%) of (2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester. (whitesolid: mp=160-161° C., [α]_(D)=−40.3° (c 1, CHCl₃).

Elemental Analysis C₁₈H₁₉NO₄·0.03H₂O

Elemental Analysis C₁₈H₁₉NO₄0.03H₂O Calc. Found C 68.86 68.99 H 6.126.07 N 4.46 4.60 H₂O 0.20 0.20

EXAMPLE 3 Preparation of (4S-trans)- and(4S-cis)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethyl esters

(2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester (66.8 mg, 0.213 mmoles)was added to an oven-dried 10 ml flask, purged with argon, and suspendedin toluene (4.0 ml). Pyridinium p-toluene sulfonic acid (49 mg, 0.195mmoles) was added. The flask was equipped with a Dean-Stark trap (filledwith 4 angstrom molecular sieves). The reaction was heated to reflux(most of the solids dissolved upon heating). TLC at 5 hours showed thatthe reaction was nearly complete (1:1 EtOAc:hexanes, PMA/EtOH, U.V.).

The reflux was allowed to continue overnight. After 22 hours of heating,the reaction was cooled to room temperature. Some oily substance droppedout of solution. This oil solidified upon further cooling to roomtemperature. The solid did not appreciably dissolve upon the addition of˜5 ml EtOAc. ˜3 ml CHCl₃ were added to dissolve all solid material. TLCshowed no starting material.

The solution was then washed with 5 ml saturated aqueous NaHCO₃, driedover Na₂SO₄, filtered, and concentrated to yield 64.3 mg of a partiallycrystallized yellow oil. ¹H and ¹³C NMR showed cis-oxazoline titleproduct: trans-oxazoline title product: impurity in a ˜5:trace:1 ratio.The trans-oxazoline title product was attributed to a trace amount of(2R,3S)-N-benzoyl-3-phenylisoserine ethyl ester present in the startingmaterial. The product was chromatographed on silica gel with 1:1EtOAc/Hexane 2:1 EtOAc/Hexane, (R_(f)=0.57 (1:1 EtOAc:hexanes) to give49.3 mg of an oily yellowish solid, yield=78.4%; ¹H NMR showed the cisand trans oxazoline title products in about a 10:1 ratio (cis:trans).

EXAMPLE 4 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, methylester

(a) Benzenecarboximidic acid, ethyl ester, hydrochloride

Benzonitrile (30.3 g, 294 mmoles) and ethanol (14.2 g, 308 mmoles) wereadded to a flame-dried, argon purged 100 ml flask and cooled to 0° C.HCl was bubbled through the stirring solution for 20 minutes, by whichtime the tare showed that 17.5 g HCl had been added. HCl addition wasceased and the clear solution was stirred at 0° C. A precipitate beganto form after about 1 hour.

After stirring at 0° C. for about 2½ hours. the heterogeneous mixturewas transferred to a 4° C. cold room. After 3½ days at 4° C., the solidmass was crushed and triturated with 150 ml of cold 4° C. diethyl ether.The mixture was allowed to stand at 4° C. for 6 hours. The mixture wasvacuum-filtered and quickly washed with 2×100 ml cold diethyl ether anddried under high vacuum (0.5 mm Hg for 17 hours) to give 51.6 g (94.5%)of a white free flowing powder of the title product.

(b) (4S-trans-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, methylester

(2R,3S)-3-Phenylisoserine methyl ester hydrochloride salt (5.76 g, 24.9mmoles) was dissolved in 1,2-dichloroethane (75 ml). Triethylamine (2.77g, 27.3 mmoles) was added and the resulting mixture was stirred for 15minutes before the addition of the benzimidate prepared in step (a)above (4.62 g, 24.9 mmoles) in one portion. The mixture was stirred for10 minutes, then heated to reflux. TLC after 4½ hours of reflux showedthe reaction to be complete. (1:1 ethyl acetate/hexane, PMA/ethanol,U.V.)

The reaction mixture was diluted with 150 ml dichloromethane and 150 ml10% K₂CO₃ and shaken. The layers were separated, and the aqueousfraction extracted with 3×50 ml CH₂Cl₂. The combined organic fractionswere washed with 50 ml saturated aqueous NaCl, dried over Na₂SO₄,filtered and concentrated to give a yellow oil which was purified on asilica gel column (dry volume ˜750 ml; packed column: 100 mm d×110 mm l)with 1:2 ethyl acetate/hexane to give 6.05 g of the title product as avery slightly colored oil which solidified upon standing at roomtemperature. Yield=86.4%.

EXAMPLE 5 Preparation of(4S-cis)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethyl ester

In a 100 ml flask containing a solution of(2R,3S)-N-benzoyl-3phenylisoserine ethyl ester (2.00 g, 6.38 mmol) inpyridine (20 ml) at 0° C. was added methanesulfonyl chloride (0.52 ml,6.70 mmol) dropwise over a 2 minute period. The solution was stirred at0 to 4° C. for 90 minutes and then at 65-70° C. for 18 hours. (Thereaction was monitored by TLC using 1:2 EtOAc:Toluene as eluent, R_(f)for the starting material=0.42, R_(f) for the mesylate=0.48 and R_(f)for the cis-oxazoline title product=0.78, UV visualization.)

The reaction was cooled down to room temperature and diluted with EtOAc(80 ml) and ⅓ saturated CuSO₄ solution (80 ml) (⅓ saturated CuSO₄solution was prepared by diluting saturated CuSO₄ solution to ⅓ itsoriginal concentration). The aqueous layer was separated and extractedwith EtOAc (40 ml×1). The combined EtOAc solution was then washed withbrine (80 ml×1), dried over Na₂SO₄, filtered, concentrated andazeotroped with heptane (20 ml×2) to give crude cis oxazoline titleproduct as a solid (1.88 g). It was dissolved in hot EtOAc (8 ml) andthen hexane (4 ml) was added. The crystallizing mixture was set aside atroom temperature for 20 minutes and then at 4° C. for 30 minutes. Thesolid was filtered, washed with cold 10% EtOAc in hexane and air driedto give 1.34 g (71.3%) of the cis-oxazoline title product having amelting point of 135° C. [a]_(D)=−9.25 (c=1.0,CHCl₃).

EXAMPLE 6 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid

(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethylester (92 mg, 0.311 mmoles) was transferred to a 1 dram vial anddissolved in tetrahydrofuran (THF) (0.8 ml). LiOH (aq., 1 N, 0.343mmoles) was added dropwise and the resulting biphasic mixture wasstirred vigorously at room temperature. Within 5 minutes, a homogeneoussolution was obtained. TLC after 45 minutes showed no starting material(1:1 ethyl acetate (EtOAc)/Hexane, PMA/ethanol (EtOH), U.V).

The solution was cooled to 0° C. and further diluted with 2.0 ml THF.The reaction was quenched with 0.34 ml of 1 N HCl (1.1 eq). Afterwarming to room temperature, the solution was diluted with 5 ml EtOAcand 5 ml H₂O and shaken. The layers were separated. The aqueous fractionwas extracted with 3×5 ml EtOAc. (After extractions, aqueous fraction pH˜6). The combined organic fractions were dried over Na₂SO₄, filtered andconcentrated to give 72.1 mg of a white solid. Yield=87%. ¹H and ¹³CNMRs, and Mass. Spec. showed the title product having a melting point of201-203° C. [a]_(D) =+25.6°, [a] ₅₇₈ =+26.9°, [a] ₅₄₆+30.7°,[a]₄₃₆=+53.8° (c=1.0 CHCl₃: CH₃OH (1:1)).

EXAMPLE 7 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid

(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, methylester (0.509 g, 1.81 mmoles) was added to a 10 ml flask and dissolved intetrahydrofuran (THF) (4.7 ml). Lithium hydroxide (1 N in H₂O, 2.0 ml,1.99 mmoles) was added dropwise. The biphasic mixture was stirredvigorously. Within 2 minutes after completion of the lithium hydroxideaddition, a clear solution was obtained. TLC after 15 minutes showedthat the reaction was complete (1:1 ethyl acetatehexane, PMA/ethanol).

The reaction mixture was further diluted with 10 ml THF and theresulting cloudy solution cooled to 0° C. The reaction was quenched bydropwise addition of 2.0 ml of 1 N aqueous HCl. The solution was furtherdiluted with 20 ml ethyl acetate and 15 ml water and shaken. The layerswere separated, and the aqueous fraction extracted with 3×10 ml ethylacetate (pH of the aqueous layer after extractions was approximately 6).The combined organic fractions were dried over Na₂SO₄ filtered, andconcentrated. The concentrate obtained was soluble in a mixture ofbenzene and methanol, and less soluble in methanol, CHCl₃, ethyl acetateor a mixture of these. The concentrate was dried on high vacuumovernight to yield 0.448 g of the title product as a white solid.(Yield=93%). M.P.=201-203°. [α]_(D)=+25.6, [α]₅₇₈=+26.9°, [α]₅₄₆=+30.7,[α]₄₃₆=+53.8°, (c=1.0, CHCl₃:CH₃OH (1:1)).

EXAMPLE 8 Preparation of(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid

Ethanol (0.1 ml) was mixed with tetrahydrofuran (1.0 ml), and themixture cooled to −78° C. n-Butyllithium (n-BuLi) (2.12M, 0.050 ml) wasadded dropwise, and the mixture warmed to 0° C. Solid(4S-cis)-4,5-dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethyl esterhaving the structure:

(20 mg, 0.0678 mmol) was added and the reaction was stirred for 1 hour(a small amount of water was present). A mixture of cis oxazoline ethylester starting material and the corresponding trans oxazoline ethylester (5-position inversion) were observed by TLC (very littlehydrolysis was noted at this point). The reaction mixture was stirredfor another hour and then left with an ice bath overnight (0° C. to roomtemperature). After 18 hours TLC showed mostly the trans acid titleproduct and a trace of the cis ester starting material (solvent systemshexane:EtOAc 2:1 (trace of cis ester) and EtOAc:acetone:H₂O:MeOH 7:1:1:1(title product)).

The reaction was quenched with phosphate (pH=4.3) buffer, and extractedwith ethyl acetate (5×10 ml). The organic layer was dried and solventremoved to give ˜17 mg (93%) of the title product. (NMR showed the transacid title product). M.P.=135° C. [a]_(D)=−92.5°, (c=1.0, CHCl₃).

EXAMPLE 9 Preparation of (4S-trans)- and(4S-cis)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acids

(4S-cis)-4,5-dihydro-2,4-diphenyl-5-oxazolecarboxylic acid, ethyl ester(202 mg, 0.6890 mmoles) was dissolved in tetrahydrofuran (1.5 ml) andlithium hydroxide (1 N aq., 0.718 ml) was added dropwise. Aheterogeneous solution was observed. The reaction mixture was stirredovernight at room temperature, upon which time the solution was clear.(TLC (ethyl acetate:hexane, 1:1) showed a small amount of startingmaterial. TLC (ethyl acetate:methanol:water:acetone 7:1:1:1) showed thecis and trans oxazoline title products).

1 N HCl (0.718 ml) was added, followed by saturated NaCl (approximately10 ml) and ethyl acetate (approximately 10 ml). The water layer waswashed with ethyl acetate 5 times (approximately 10 ml) and the H₂Olayer which had a pH of ˜5.5 was further acidified to 3.4 pH andextracted with approximately 10 ml EtOAc. The combined organic layerswere dried over MgSO₄, and filtered. The ethyl acetate was evaporatedunder reduced pressure to yield 183 mg (100%) of a mixture of cis andtrans title products (3:1, cis:trans by ¹ H NMR).

EXAMPLE 10 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl]baccatinIII

(a) 7-Triethylsilyl baccatin III

(i) [2aR-(2aα,4β,4aβ,6β,9α,11β,12α, 12aα, 12bα)]-Benzoic acid,12b-acetyloxy-2a,3,4,4a,5,6,-9,10,11,12,12a,12b-dodecahydro-6,9,11-trihydroxy-4a,8,13,13-tetramethyl-5-oxo-4-[(triethylsilyl)oxy]-7,11-methano-1H-cyclo-deca[3,4]benz[1,2-b]oxet-12-yl ester

10-Desacetylbaccatin III (27.4 g, 50.3 mmol, containing H₂O:1.57%,CH₃OH:1.6%, ethyl acetate:0.09%, and hexane:0.03%), and4-dimethylaminopyridine (2.62 g, 21.4 mmol, wt. % H₂O (Karl Fisher (“K.F.”)=0.09) were added to a flame-dried, argon-purged 1 L 3-necked flask(equipped with a mechanical stirrer and a digital thermometer) and weredissolved in dry dimethylformamide (122 ml, wt. % H₂O (K. F.)=<0.01).Methylene chloride (256 ml, wt. % H₂O (K. F.)=<0.01) was added (thetemperature of the reaction solution rose from 23° C. to 25° C. duringthe addition of the methylene chloride) and the resulting homogeneoussolution was cooled to −50° C.

Triethylamine (16 ml, 120 mmol, wt. % H₂O (K. F.)=0.08) was addeddropwise over 3 minutes and the resulting solution was stirred at −50°C. for 5 minutes before the dropwise addition of neat triethylsilylchloride (18.6 ml, 111 mmol). The addition of triethylsilyl chloride wasconducted over a period of 10 minutes during which the temperature ofthe reaction did not rise above −50° C. The reaction became very cloudyduring the addition of triethylsilyl chloride.

The resulting mixture was stirred at about −50° C. for 1 hour and wasthen allowed to stand (without stirring) in a −48° C. freezer for 22hours. (A separate experiment showed that stirring the reaction at −48°C. for 8 hours resulted in ˜60% conversion). The mixture was thenremoved from the freezer and warmed to about −10° C. TLC analysis of themixture (solvent:ethyl acetate, stain:phosphomolybdic acid/ethanol)revealed the absence of starting material and showed a single spot forthe product (R_(f)=0.60). The cold mixture was combined with EtOAc (1 L)and washed with H₂O (890 ml).

The resulting aqueous layer was separated and extracted with EtOAc (250ml). The combined organic layers were washed with 5.7% aqueous NaH₂PO₄(2×250 ml, measured pH of 5.7% aqueous NaH₂PO₄=4.30±0.05, measured pH ofthe combined NaH₂PO₄ washings=5.75±0.05), half-saturated aqueous NaCl(250 ml), saturated aqueous NaCl (250 ml), dried over Na₂SO₄, filteredand concentrated on a rotovap. (All concentrations on the rotovap ofthis Example were conducted with a water bath temperature of 35° C.)

The resulting semi-solid was further dried by exposure to high vacuum(˜1 mm Hg for 20 minutes) to give 41.5 g of a white solid. The crudeproduct was then dissolved in CH₂Cl₂ (400 ml) (heating in a 35° C. waterbath was employed to dissolve the solid), and the volume of theresulting solution was reduced to ˜150 ml on a rotovap. Crystallizationstarted immediately and the mixture was allowed to stand at roomtemperature for 1 hour. Hexanes (100 ml) were added and the mixture wasgently swirled. The mixture was allowed to stand in a 4° C. cold roomfor 16.5 hours. The solid was filtered, washed with 1:9 CH₂Cl₂/hexanes(3×250 ml) on a suction filter, and dried under high vacuum (˜0.2 mm Hgfor 42 hours) to give 26.1 g (79%) of the title product as a whitepowder. The mother liquor was concentrated on a rotovap, and the residuewas crystallized from CH₂Cl₂ to give 4.5 g (14%) of the title product aswhite crystals. Recrystallization was conducted in the same manner aswith the first crop of product: the solid was dissolved in CH₂Cl₂ (100ml) without heating, and the volume of the resulting solution wasreduced to ˜7 ml on a rotovap. Crystallization began within 5 minutes.The mixture was allowed to stand at room temperature for 1 hour, then ina 4° C. cold room for 42 hours. The crystals were filtered, washed with1:9 CH₂Cl₂/hexanes (3×50 ml) on a suction filter, and dried under highvacuum (˜0.2 mm Hg for 18 hours). The ¹H NMR of this crop was identicalto the ¹ H NMR of the first crop of product. The combined yield for thetwo crops was 93% (uncorrected).

Elemental Analysis (%) C₃₅H₅₀O₁₀Si Calcd. Found C 63.80 63.43 H 7.657.66 KF(H₂O) 0.00 0.00

m.p.: 239-242° C. (decomp.) [α]²² _(D): −53.6° (c 1.0, CHCl₃) TLC:R_(f)=0.60 (silica gel, EtOAc) Visualized by phosphomolybdicacid/ethanol.

(ii)[2aR-(2aα,4β,4aβ,6β,9α,11β,12α,12aα,12bα)]-6,12b-Bis(acetyloxy)-12-(benzoyloxy)-2a,-3,4,4a,5,6,9,10,11,12,12a,12b-dodecahydro-9,11-dihydroxy-4a,8,13,13-tetramethyl-4-[(triethylsilyl)oxy]-7,11-methano-1H-cyclo-deca[3,4]benz[1,2-b]oxet-5-one(7-triethylsilyl baccatin III)

The title product from step (i) above (21.4 g, 32.4 mmol) was added to aflame-dried, argon purged 1 L 3-necked flask (equipped with a mechanicalstirrer and a digital thermometer) and dissolved in THF (350 ml, freshlydistilled from sodium/benzophenone). The resulting solution was cooledto −70° C. A solution of n-butyllithium (n-BuLi) (14.6 ml of a 2.56 Msolution in hexanes, 37.3 mmol, titrated in triplicate withdiphenylacetic acid in THF at 0° C.) was added dropwise over a period of23 minutes. The temperature of the reaction did not rise above −68° C.during the addition. Solids were formed upon the addition of n-BuLi anddid not appear to dissolve at −70° C. The resulting mixture was stirredat −70° C. for 20 minutes and was then warmed to −48° C. A clearhomogeneous solution was obtained upon warming to −48° C.

After stirring at −48° C. for ½ hour, acetic anhydride (4.6 ml, 49 mmol,distilled (137-138° C., 1 atm) under an atmosphere of argon before use)was added dropwise over 7 minutes. The temperature of the reaction didnot rise above −45° C. during the addition. The resulting solution wasstirred at −48° C. for 20 minutes and then at 0° C. for 1 hour. Thesolution was diluted with ethyl acetate (350 ml), washed with saturatedaqueous NH₄Cl (250 ml), and the layers were separated. The aqueous layerwas extracted with ethyl acetate (200 ml). The combined organic layerswere washed with saturated aqueous NaCl, dried over Na₂SO₄, filtered andconcentrated on a rotovap. (All concentrations on the rotovap in thisExample were conducted with a water bath temperature of 35° C.) Exposureof the semi-solid to high vacuum (˜1.5 mm Hg for ½ hour) gave 24.7 g ofa white solid.

The crude product was dissolved in CH₂Cl₂ (300 ml) and the volume of theresulting solution was reduced to ˜70 ml on a rotovap. Crystallizationbegan within one minute. The mixture was allowed to stand at roomtemperature for 45 minutes and then in a 4° C. cold room for 18 hours.The crystals were filtered, washed with 1:9 CH₂Cl₂/hexanes (3×100 ml) ona suction filter, and dried under high vacuum (˜0.2 mm Hg for 19 hours)to give 20.9 g (92.0%) of the title product as fine white needles. Themother liquor was concentrated on a rotovap, and the residue wascrystallized from CH₂Cl₂/hexanes to give 0.82 g (3.6%) of the titleproduct as small white crystals.

Crystallization of the mother liquor was conducted as follows: Theresidue was dissolved in CH₂Cl₂ (10 ml) and the volume of the resultingsolution was reduced to ˜5 ml on the rotovap. After standing at roomtemperature for ½ hour, no crystals had formed. Hexanes (5 ml) wereadded in 1 ml portions and the solution was swirled. A few crystals werepresent by this time. The mixture was allowed to stand at roomtemperature for ½ hour (more crystals formed) and then in a 4° C. coldroom for 18 hours. The crystals were filtered, washed with 1:9CH₂Cl₂/hexanes on a suction filter, and dried under high vacuum (˜0.15mm Hg for 21 hours). The combined yield for the two crops was 95.6%.m.p.=218-219° C. (decomp.); [α]²² _(D)=−78.4° (c 1.0, CHCl₃);TLC:R_(f)=0.37 (silica gel, 1:9 acetone: CH₂Cl₂, visualized byphosphomolybdic acid/ethanol).

(b) 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl]baccatinIII

7-Triethylsilyl baccatin III prepared in step (a) above (0.209 g, 0.298mmoles), the oxazoline prepared as the title product of Example 6 (80.2mg, 0.300 mmoles), dicyclohexylcarbodiimide (DCC) (84 mg, 0.407 mmoles),and 4-dimethylaminopyridine (DMAP) (25 mg, 0.205 mmoles) were added to a1 dram vial (oven-dried), purged with argon, and suspended in toluene(1.0 ml). After stirring for 1 hour at room temperature, some of thesolid had dissolved and the mixture was a yellowish color. Theheterogeneous mixture was heated to 85° C. TLC at 2½ hours showed thepresence of starting material (1:1 ethyl acetate:hexane, PMA/ethanol,U.V.). Heating at 85° C. was continued. TLC at 5 hours lookedessentially the same. The reaction was allowed to stir at roomtemperature overnight. After 14 hours at room temperature, TLC remainedthe same. The heterogeneous mixture was diluted with 1.0 ml ethylacetate (some precipitate was noted) and the mixture was filteredthrough a pad of Celite. The Celite was rinsed with 3×1 ml ethylacetate, and the filtrate was concentrated to give 0.349 g of ayellowish solid. ¹H NMR showed that the title product and7-triethylsilyl baccatin III were present in an approximately 8:1 ratio,respectively; some 1,3-dicyclohexylurea (DCU), and a trace of either thestarting oxazoline or an impurity were also noted.

The mixture was partially separated on silica gel (column: 20 mmdiameter×90 mm length) with 1:2 ethyl acetate/hexane to 1:1 ethylacetate/hexane. During chromatography, TLC analysis revealed a smallspot with a slightly lower R_(f) than the coupled title product. Themixed fractions of this impurity and the coupled product were combined.First spot: coupled title product (0.267 g of an off-white solid,yield=94%.) (¹H NMR showed an approximately 18:1 ratio of the desiredcoupled product and the aforementioned impurity); first spot andaforementioned mixed fractions: 11.5 mg of an oil (¹H NMR showed anapproximately 2:1 ratio of the desired coupled product and a differentimpurity). M.P.=139-142° C. [a]_(D)=−49.5°, [α]₅₇₈=−52.6°,[α]₅₄₆=−63.5°, [α]₄₃₆=−157.0°, (c=1.0, CHCl₃).

EXAMPLE 11 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl]baccatinIII

(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid (96.0 mg,0.359 mmoles), 7-triethylsilyl baccatin III (0.252 g, 0.359 mmoles), and4-dimethylaminopyridine (DMAP)(30 mg, 0.246 mmoles) were added to aflame-dried 1 dram vial, purged with argon and suspended in toluene (1.2ml). Diisopropylcarbodiimide (DIC)(63 mg, 0.503 mmoles) was immediatelyadded, and the slightly yellowish heterogeneous mixture was stirred atroom temperature. As time progressed, a very cloudy yellow solutionresulted. At this point, the vial was sealed and immersed in an 80° C.oil bath. After 3 hours at ˜80° C., a darker orangish solution wasobtained. The reaction mixture was directly concentrated. ¹H NMR showed˜6:1 ratio of the desired coupled product and 7-triethylsilyl baccatinIII. The product was partially purified by silica gel chromatographywith 1:3 EtOAc/Hexane to give 0.300 g of an off-white solid. TLC showedisolated product and diisopropyl urea by-product.

¹ H NMR showed only the desired coupled product and an impurity in ˜25:1ratio, and diisopropyl urea by-product. The ratio of desired coupledproduct to the diisopropyl urea by-product was ˜12:1.

From these results, the yield of the desired coupled product was ˜85%.M.P.=139-142° C. [α]_(D)=−49.5°, [α]₅₇₈=52.6°, [α]₅₄₆=−63.5°,[α]₄₃₆=−157.0°, (c=1.0, CHCl₃).

EXAMPLE 12 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,5-diphenyl-5-oxazolyl]-carbonyl]baccatinIII

7-Triethylsilyl baccatin III (abbreviated as “A” in this Example) and(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolecarboxylic acid(abbreviated as “B” in this Example) were contacted under the conditionsset forth in the following Table 1 to prepare the title compound.M.P.=139-142° C. [α]_(D)=−49.5°, [α]₅₇₈=−52.6°, [α]₅₄₆=−63.5°,[α]₄₃₆=−157.0°, (c=1.0, CHCl₃).

TABLE 1 Concen- Example B Reagents tration Time Temp. No. (eq.)* (eq.)*Solvent B (M) (hrs) (° C.) 12a 1.2 DCC (1.4) PhCH₃ 0.29 1 23 DMAP (0.7)2.5 85 12b 1.0 DCC (1.4) PhCH₃ 0.30 5.5 85 DMAP (0.7) 12c 1.0 R₂POCl(1.04) 1,2-DCE 0.28 6 23 DMAP (1.01) 15 55 NEt₃ (1.04) 12d 1.0 R₂POCl(1.01) 1,2-DCE 0.23 5 23 NEt₃ (2.0) 16 65 44 75 12e 1.0 CDI (1.2) THF0.39 21 70 DMAP (1.0) 12f 1.0 ArCOCl (1.5) CH₂Cl₂ 0.23 23 23 DMAP (2.0)NEt₃ (1.5) 12g 1.0 ArCOCl (1.5) PhCH₃ 0.29 5.5 23 DMAP (2.0) NEt₃ (1.5)12h 1.0 ArCOCl (1.05) CH₂Cl₂ 0.30 3.5 −78 DMAP (2.0) 19 −60 NEt₃ (1.0) 10 20 23 12i 1.0 t-BuCOCl (1.1) 1,2-DCE 0.28 4.5 23 DMAP (2.0) NEt₃ (1.2)15 60 12j 2.1 t-BuCOCl (2.1) 1,2-DCE 0.23 21 23 DMAP (4.2) NEt₃ (2.3)12k 1.0 t-BuCOCl (1.0) CH₂Cl₂ 0.24 19 23 DMAP (0.07) NEt₃ (2.0) 12l 1.0t-BuCOCl (1.0) Pyridine 0.23 4.5 23 DMAP (0.05) 16 55 23 23

* eq.=equivalents, based on 7-triethyl-silylbaccatin III (amounts of7-triethylsilyl baccatin III were the following for the above Examples:12a=0.061 g; 12b=0.533 g; 12c=0.200 g; 12d=0.161 g; 12e=0.057 g;12f=0.200 g; 12 g=0.203 g; 12h=0.208 g; 12i=0.196 g; 12j=0.165 g;12k=0.165 g; 12l=0.164 g)

Key to Table 1

R₂POCl=

=bis(2-oxo-3-oxazolidinyl)-phosphinic chloride

DCC=dicyclohexylcarbodiimide

DMAP=4-dimethylaminopyridine

DIC=diisopropylcarbodiimide

ArCOCl=2,4,6-trichlorobenzoyl chloride=

CDI=carbonyl diimidazole

t-BuCOCl=pivaloyl chloride

1,2-DCE=1,2-dichloroethane

NEt₃=triethylamine

THF=tetrahydrofuran

PhCH₃=toluene

EXAMPLE 12a

All reagents were mixed together before addition of the solvent. 108%(90 mg) of the title product was isolated by chromatography (containingabout 10% of an impurity). Starting compound A was not visible by NMR.(Concentration of B in this Example was 0.29M. A separate experimentwherein DCC (2.0 eq), DMAP (3.0 eq.), DMAP.HCl (2.0 eq.) in CHCl₃ and1.0 eq. of B was employed demonstrated that a molar concentration of0.07M B did not allow the reaction to proceed rapidly enough to observethe formation of the title product by NMR in 27 hours.)

EXAMPLE 12b

All reagents were mixed together before addition of the solvent. Thetitle product was obtained in about a 9:1 ratio to the starting compoundA (by NMR). 87% (0.63 g) of the title product was isolated bychromatography.

EXAMPLE 12c

All reagents were mixed together before addition of the solvent. Thetitle product was obtained in about a 1:1 ratio to the starting compoundA (by NMR). No further reaction progress was noted after 1 hour.

EXAMPLE 12d

Activated oxazoline B was allowed to form for 1 hour (by addition ofR₂POCl to starting compound B) before addition of starting compound A.The title product was obtained in about a 1:6 ratio to the startingcompound A (by NMR). Little reaction progress was noted after 5 hours.

EXAMPLE 12e

CDI and the starting compound B were contacted for 1 hour beforeaddition of the starting compound A. DMAP was added at t=4 hours. Abouta 1:1:1 ratio of the title compound to the starting material A and animpurity was obtained (by NMR). It was noted that no reaction occurredbefore addition of the DMAP, and that excessive heating caused somedecomposition.

EXAMPLE 12f

ArCOCl was added last. About a 1:1 ratio of the title product to thestarting compound A was obtained (by NMR). No further reaction progresswas noted after 1.5 hours.

EXAMPLE 12g

ArCOCl was added last. About a 1:1 ratio of the title product to thestarting compound A was obtained (by NMR). No further reaction progresswas noted after 1 hour.

EXAMPLE 12h

ArCOCl was added last. About a 1:1 ratio of the title product to thestarting compound A was obtained (by NMR). No further reaction progresswas noted after 3.5 hours.

EXAMPLE 12i

A mixed anhydride was preformed for 1 hour (by addition of t-BuCOCl tostarting compound B) before addition of the starting compound A. About a1:2 ratio of the title product to the starting compound A was obtained(by NMR). No further reaction progress was noted after 2 hours.

EXAMPLE 12j

A mixed anhydride was preformed for 1 hour (by addition of t-BuCOCl tostarting compound B) before addition of the starting compound A. About a3:1 ratio of the title product to the starting compound A was obtained(by NMR). No further reaction progress was noted after 1 hour.

EXAMPLE 12k

A mixed anhydride was preformed for 1 hour (by addition of t-BuCOCl tostarting compound B) before the addition of the starting compound A.DMAP was added 1 hour after the starting compound A. About a 1:4 ratioof the title compound to the starting compound A was obtained (by NMR).No reaction was observed without DMAP; no further reaction progress wasnoted after 2 hours after DMAP addition.

EXAMPLE 12l

A mixed anhydride was preformed for 1 hour (by addition of t-BuCOCl tostarting compound B) before addition of the starting compound A. DMAPwas added after 16 hours at 55° C. About a 1:6 ratio of the titleproduct to the starting compound A was obtained (by NMR). No or verylittle reaction was observed before addition of the DMAP.

EXAMPLE 13 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl] baccatinIII

(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid (65.0 mg,0.243 mmoles), 7-triethylsilyl baccatin III (0.142 g, 0.203 mmoles), DCC(75 mg, 256 mmoles), and pyrrolidinopyridine (38 mg, 256 mmoles) wereadded to a flame-dried 1 dram vial, purged with argon and partiallydissolved in toluene (1.0 ml). The resulting yellowish heterogeneousmixture was stirred at room temperature. TLC at 3 hours showed thepresence of the title product (1:1 EtOAc:hexanes, PMA/EtOH, U.V.) (TLCat 7 and 23 hours after stirring at room temperature showed no furtherchange.)

The reaction mixture was diluted with ethyl acetate (1 ml), filteredthrough a pad of celite and concentrated to give 0.275 g of an oilyyellowish solid. ¹H NMR showed the desired coupled title product and7-triethylsilyl baccatin III in ˜8:1 ratio. The N-acyl urea by-productof the coupling agent was also present in about the same amount as7-triethylsilyl baccatin III.

The solid was chromatographed on silica gel with 1:2 EtOAc/hexane togive 0.176 g of an off-white solid. Yield ˜91%. ¹H NMR showed only thedesired coupled product and the N-acyl urea in ˜11:1 ratio.

EXAMPLE 14 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl] baccatinIII

(4S-trans)-4,5-Dihydro-2,4-diphenyl-5-oxazolecarboxylic acid (66.7 mg,0.250 mmoles), 7-triethylsilyl baccatin III (0.146 g, 0.208 mmoles), DCC(79 mg, 0.383 mmoles), and 4-morpholino pyridine (41 mg, 0.250 mmoles)were added to a flame-dried 1 dram vial, purged with argon, andpartially dissolved in toluene (1 ml). The resulting yellowheterogeneous mixture was stirred at room temperature. TLC at 3 hoursshowed the presence of the title product (1:1 EtOAc:hexane, PMA/EtOH,U.V.). (TLC at 7 and 23 hours after stirring at room temperature showedno further change.)

The reaction mixture was diluted with ethyl acetate (1 ml), filteredthrough a pad of Celite, and concentrated to give 0.280 g of a yellowishsolid. ¹H NMR showed the desired coupled title product and no7-triethylsilyl baccatin III (although a trace was visible by TLC). TheN-acyl urea by-product from the coupling agent was present in a ratio totitle product of ˜1:9.

The solid was chromatographed on silica gel with 1:2 EtOAc:hexanes togive 0.196 g of a white solid. ¹H NMR showed only the coupled titleproduct and the N-acyl urea in about a 15:1 ratio. Yield greater than90%. M.P.=139-142° C. [α]_(D)=−49.5°, [α]₅₇₈=−52.6°, [α]₅₄₆−=63.5°,[α]₄₃₆=−157.0° (c=1.0, CHCl₃).

EXAMPLE 15 Preparation of 7-Triethylsilyl13-[[(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]-carbonyl] baccatinIII and 7-Triethylsilyl13-[[(4S-cis)-4,5-dihydro-2,4-diphenyl-5-oxazolyl]carbonyl] baccatin III

A mixture of the cis and trans oxazoline title products of Example 9 ina 3:1 ratio of cis: trans (100 mg), 7-triethylsilyl baccatin III (219mg, 0.3121 mmol), DCC (97 mg) and DMAP (23 mg) in toluene (0.9 ml) wasprepared. After one hour of heating at 80° C. there was a considerableamount of 7-triethylsilyl baccatin III unreacted. Another charge of DMAP(97 mg) and DCC (23 mg) was added, and the mixture heated at 80° C.overnight. Small amounts of starting material were observed by TLC(hexane:EtOAc 2:1).

The reaction mixture obtained was diluted with methylene chloride (20ml), saturated sodium bicarbonate (10 ml, aq.) was added and the waterlayer was extracted with methylene chloride (2×10 ml), and the combinedorganic layers dried over anhydrous MgSO₄. Upon concentration in vacuo,the product was purified on HPLC (hexane:ethyl acetate 4:1) to give amixture of the title products containing dicyclohexylurea (DCU). Theproduct had a weight of 260 mg after resuspension in ethyl acetate andremoval of some DCU by filtration. Another HPLC purification gave 117 mgof the pure trans title product (40%) and 45 mg of a mixture (˜2:1 transtitle product:cis title product (15%)). The mixture was purified bypreparative TLC (hexanes:ethyl acetate, 1:1) to give 11 mg of the cistitle product.

EXAMPLE 16 Preparation of Taxol

The coupled title product obtained in Example 10 above (0.102 g, 0.107mmoles) was weighed into a 10 ml flask and dissolved in tetrahydrofuran(1.2 ml). Methanol was then added (1.2 ml) and the homogeneous solutioncooled to 0° C. HCl (aq., 1 N, 0.59 ml, 0.59 mmoles) was added dropwiseand the clear homogeneous solution was stirred at 0° C. After 3 hours at0° C., TLC (1:1 ethyl acetate:hexane, PMA/ethanol, U.V.) indicatedstarting material remained, and the clear homogenous solution wastransferred to a 4° C. cold room. After 18 hours at 4° C., TLC analysisshowed the reaction to be essentially complete (1:1 ethylacetate:hexane, PMA/ethanol, U.V.). The following compound was obtained:

The clear homogeneous solution was warmed to room temperature. 3.5 mlsaturated aqueous NaHCO₃ was added (bubbling was noted) to yield aheterogeneous mixture. Addition of 5 ml tetrahydrofuran and 2 ml waterdid not significantly enhance the solubility. The heterogeneous mixturewas stirred vigorously at room temperature. After stirring at roomtemperature for 1 hour, a heterogeneous mixture was still present. Themixture was further diluted with 7 ml water and 4 ml tetrahydrofuran.The resulting clear homogeneous solution was stirred at roomtemperature.

TLC at 2½ hours after NaHCO₃ addition showed only the presence of taxol(2:1 ethyl acetate/hexane, PMA/ethanol, U.V.). The reaction mixture wasdiluted with 25 ml ethyl acetate and 25 ml water and shaken. The layerswere separated, and the aqueous fraction extracted with 3×25 ml ethylacetate. The combined organic fractions were dried over Na₂SO₄, filteredand concentrated to give 104 mg of a slightly off-white glassy solid. ¹HNMR showed taxol. The solid obtained was purified by chromatography onsilica gel (column: 20 mm diameter×70 mm length) with 2:1 ethylacetate/hexane to 4:1 ethyl acetate/hexane to give 79.0 mg of the titleproduct as a white solid. Yield=86.4%.

EXAMPLE 17 Preparation of 7,13-BisTES Baccatin

Baccatin III (3.102 g, 5.290 mmol) was dissolved in dry DMF (21 mL). Tothis solution at 0° C. was added imidazole (1.80 g, 26.5 mmol), followedby TESCl (4.45 mL, 26.5 mmol). The reaction was stirred at roomtemperature overnight and diluted with EtOAc (350 mL), and washed withwater (4×20 mL) and brine. The organic layer was dried and concentratedin vacuo the residue was chromatographed (20% ethyl acetate in hexanes)to afford 4.00 g (89.1%) of the desired product.

EXAMPLE 18 Preparation of 1-DMS-7,13-TES Baccatin

7,13-TES baccatin (2.877 g, 3.534 mmol) was dissolved in dry DMF (17.7mL). To this solution at 0° C. was added imidazole (720.9 mg, 10.60mmol), followed by dimethylchlorosilane 91.18 mL, 10.60 mmol). Thereaction was stirred at that temperature for 45 minutes, and thendiluted with EtOAc (300 mL) and washed with water (4×20 mL). The organicphase was dried and concentrated in vacuo. The residue waschromatographed (10% ethyl acetate in hexanes) to afford 2.632 g (85.4%)of the desired product.

EXAMPLE 19 Preparation of 4-Hydroxy-7,13-BisTES-1-DMS Baccatin

The silylated baccatin derivative of Example 18 (815 mg, 0.935 mmol) wasdissolved in THF (15.6 mL). To this solution at 0° C. was added Red-Al(0.910 mL, 60% wt, 4.675 mmol). After 40 minutes, the reaction wasquenched with saturated sodium tartrate solution (7 mL). After 5minutes, the reaction mixture was diluted with EtOAc (250 mL).Theorganic phase was washed with water and brine and dried. The organiclayer was then concentrated in vacuo, the residue was chromatographed(10-20% ethyl acetate in hexanes) to afford 590 mg (76.0%) of thedesired C4-hydroxyl baccatin analog.

EXAMPLE 20 Preparation of C4-Cyclopropyl ester -7,13-BisTES-1-DMSbaccatin

The C4-hydroxyl baccatin derivative of Example 19 (196 mg, 0.236 mmol)was dissolved in dry THF (4.7 mL). This solution at 0° C. was treatedwith LHMDS (0.283 mL, 1 M, 0.283 mmol), after 30 minutes at thattemperature, cyclopropanecarbonyl chloride (0.032 mL, 0.354 mmol) wasadded. The reaction was stirred at 0° C. for 1 hour and then quenchedwith saturated NH₄Cl (3 mL). The reaction mixture was extracted withEtOAc (100 mL), and washed with water and brine. The organic layer wasdried and concentrated in vacuo. The resulting residue waschromatographed (10% ethyl acetate in hexanes) to afford 137 mg (65%) ofthe desired product.

EXAMPLE 21 Preparation of C4-Cyclopropane ester baccatin

7,13-TES-1-DMS-4-cyclopropane baccatin of Example 20 (673 mg, 0.749mmol) was dissolved in dry acetonitrile (6 mL) and THF (2 mL). To thissolution at 0° C. was added pyridine (2.25 mL), followed by 48% HFsolution (6.74 mL). After 30 minutes at 0° C., TBAF (2.25 mL, 1 M, 2.25mmol) was added. Additional dose of TBAF was added until startingmaterial was consumed as judged by TLC. The reaction mixture wasconcentrated to a syrup, and then diluted with EtOAc (350 mL) and washedwith 1 N HCl, NaHCO3 saturated solution, brine and concentrated invacuo. The residue was chromatographed (60% ethyl acetate in hexanes) toafford 366 mg (80%) of the desired product.

EXAMPLE 22 Preparation of 7-TES-4-Cyclopropane Baccatin

4-cyclopropane baccatin of Example 21 (46.6 mg, 0.076 mmol) wasdissolved in dry DMF (1 mL). To this solution at 0° C. was addedimidazole (20.7 mg, 0.305 mmol), followed by TESCl (0.0512 mL, 0.305mmol). The reaction was stirred at 0° C. for 30 minutes and diluted withEtOAc (50 mL). The reaction mixture was washed with water and brine anddried then concentrated in vacuo. The residue was chromatographed(30-50% ethyl acetate in hexanes) to afford 36 mg (65.1%) of the desiredproduct.

EXAMPLE 23 Preparation of 2′,7-BisTES-4-Cyclopropane Paclitaxel

A THF (1 mL) solution of the compound of Example 22 (30.0 mg, 0.0413mmol) was cooled to −40° C. and treated with LHMDS (0.062 mL, 0.062mmol). After 5 minutes, a THF solution (0.5 mL) of β-lactam* (23.6 mg,0.062 mmol) was added. The reaction was stirred at 0° C. for 1 hour, andthen quenched with saturated NH₄Cl solution (1 mL). The reaction mixturewas extracted with EtOAc (40 mL) and washed with water and brine. Theorganic phase was dried and concentrated in vacuo, the residue waschromatographed (20-30-60% ethyl acetate in hexanes) to afford 24.5 mg(53.6%) of the desired product together with 5.1 mg (17%) of thestarting material.

*Methods for preparing this beta-lactam are found in U.S. Pat. No.5,175,315

EXAMPLE 24 Preparation of 4-Cyclopropane ester of paclitaxel

An acetonitrile solution (0.5 mL) of the product of Example 23 (22.0 mg,0.020 mmol) was treated at 0° C. with pyridine (0.060 mL), followed by48% HF solution (0.180 mL). The reaction mixture was kept at 5° C.overnight and then diluted with EtOAc (30 mL), and washed with water andbrine. The organic layer was dried and concentrated in vacuo. Theresidue was chromatographed (60% ethyl acetate in hexanes) to afford10.0 mg (57.2%) of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.10-8.06 (m, 2H), 7.76-7.26 (m, 13H), 7.04(d, J=9.1 Hz, 1H), 6.27 (s, 1H), 6.14 (m, 1H), 5.82 (d, J=9.1 Hz, 1H),5.65 (d, J=6.9 Hz, 1H), 4.85 (m, 2H), 4.39 (m, 1H), 4.19 (AB q, J=8.4Hz, 2H), 3.80 (d, J=6.9 Hz, 1H), 3.59 (d, J=4.8 Hz, 1H), 2.60-1.13 (m,24H, incl. singlets at 2.23. 1.77, 1.66, 1.23, 1.14, 3H each).

HRMS calcd. for C₄₉H₅₄NO₁₄ (MH⁺): 880.3544, found: 880.3523.

EXAMPLE 25 Preparation of 7,13-TES-1-DMS-4-Cyclobutyl ester baccatin

A THF solution (2.6 mL) of the product of Example 19 (113.6 mg, 0.137mmol) was treated at 0° C. with LHMDS (0.178 mL, 1 M, 0.178 mmol). After30 minutes at 0° C., cyclobutylcarbonyl chloride (24.4 mg, 0.206 mmol)was added. The reaction was stirred at 0° C. for 1 hour and quenchedwith NH₄Cl saturated solution (2 mL). The reaction mixture was extractedwith EtOAc (75 mL), washed with water and brine. The organic layer wasdried and concentrated in vacuo. The residue was chromatographed (10%ethyl acetate in hexanes) to afford 80 mg (64.1%) of the desiredproduct.

EXAMPLE 26 Preparation of 4-Cyclobutyl baccatin

To an acetonitrile solution (3 mL) of the compound of Example 25 at 0°C. was added dry pyridine (0.61 mL), followed by 48% HF (1.83 mL). After1 hour at 0° C., TBAF (0.61 mL, 1 M, 0.61 mmol) was added. AdditionalTBAF was added until all of the starting material was consumed. Thesolvent was then partially removed, and the residue was diluted withEtOAc (150 mL), and washed with 1 N HCl and NaHCO₃ saturated solution.The organic layer was then dried and concentrated in vacuo.

The residue was chromatographed (60% ethyl acetate in hexanes to afford95.6 mg (75%) of the desired product.

EXAMPLE 27 Preparation of 7-TES-4-Cyclobutyl ester baccatin

4-cyclobutyl baccatin of Example 26 (85 mg, 0.136 mmol) was dissolved indry DMF (1.4 mL). To this solution at 0° C. was added imidazole (36.9mg, 0.543 mmol) and TESCl (91.2 uL, 0.543 mmol). The reaction mixturewas diluted with EtOAc (75 mL) and washed with water and brine. Theorganic layer was dried and concentrated in vacuo. The residue waschromatographed (40% ethyl acetate in hexanes) to afford 74 mg (73.6%)of the desired product.

EXAMPLE 28 Preparation of 2′,7-TES-4-Cyclobutyl Paclitaxel

7-TES-4-cyclobutyl baccatin of Example 27 (41 mg, 0.055 mmol) wasdissolved in THF (1 mL). This solution was cooled to −40° C. and treatedwith LHMDS (0.083 mL, 1 M, 0.083 mmol), followed by a THF solution (0.5mL) of β-lactam of Example 23 (31.7 mg, 0.083 mmol). The reaction waskept at 0° C. for 1 hour and quenched with NH₄Cl (2 mL). The reactionmixture was extracted with EtOAc (50 mL), and washed with water andbrine. The organic layer was then dried and concentrated in vacuo, theresidue was chromatographed (20-30% ethyl acetate in hexanes) to afford56 mg (90.2%) of the desired product.

EXAMPLE 29 Preparation of 4-Cyclobutyl Paclitaxel

2′,7-TES-4-cyclobutyl taxol of Example 28 (47 mg, 0.042 mmol) wasdissolved in acetonitrile (1 mL), to this solution at 0° C. was addedpyridine (0.125 mL), followed by 48% HF (0.375 mL). The reaction waskept at 5° C. overnight. The reaction was then diluted with EtOAc (50mL), washed with 1 N HCl, NaHCO₃ saturated solution and brine. Theorganic layer was dried and concentrated in vacuo. The residue waschromatographed (60% ethyl acetate in hexanes) to afford 31.8 mg (84.9%)of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.15-8.12 (m, 2H), 7.73-7.26 (m, 13H), 6.96(d, J=9.0 Hz, 1H), 6.26 (s, 1H), 6.17 (m, 1H), 5.80 (d, J=9.0 Hz, 1H),5.66 (d, J=7.1 Hz, 1H), 4.83 (m, 2H), 4.41 (m, 1H), 4.26 (AB q, J=8.4Hz, 2H), 3.78 (d, J=7.0 Hz, 1H), 3.57 (d, J=5.2 Hz, 1H), 3.42 (m, 1H),2.61-1.14 (m, 25H, incl. singlets at 2.23, 1.76, 1.68, 1.23, 1.14, 3Heach).

HRMS calcd. for C₅₀H₅₆NO₁₄ (MH⁺): 894.3701, found: 894.3669.

EXAMPLE 30

Preparation of 7,13-TES-1-DMS-4-Cyclopentyl ester of baccatin

A THF solution (3.5 mL) of the compound of Example 19 (147 mg, 0.177mmol) was treated at 0° C. with LHMDS (0.230 mL, 1 M, 0.230 mmol). After30 minutes, cyclopentylcarbonyl chloride (32.3 uL, 0.266 mmol) wasadded. The reaction was stirred for 1 hour at that temperature, and thenquenched with NH₄Cl saturated solution. The reaction mixture wasextracted and washed and dried, and concentrated in vacuo. The residuewas chromatographed (10% ethyl acetate in hexanes) to afford 90 mg (55%)of the desired product.

EXAMPLE 31

Preparation of 4-Cyclopentyl baccatin

An acetonitrile solution (1.6 mL) of the product of Example 30 (75 mg,0.081 mmol) was treated at 0° C. with pyridine (0.24 mL), followed by48% HF (0.72 mL). The reaction was stirred at 0° C. for 1 hour, and thenTBAF (0.405 mL, 1 M, 0.405 mmol) was added. Another five eqivalent ofreagent was added after 1 hr. The reaction mixture was diluted withEtOAc (100 mL), and washed with 1 N HCl and NaHCO₃ saturated solutionand brine. The organic layer was dried and concentrated in vacuo. Theresidue was chromatographed (50% ethyl acetate in hexanes) to afford 44mg (85%) of the desired product.

EXAMPLE 32 Preparation of 7-TES-4-Cyclopentyl ester baccatin

4-cyclopentyl baccatin (35 mg, 0.055 mmol) was dissolved in dry DMF (1mL). To this solution at 0° C. was added imidazole (14.9 mg, 0.219mmol), followed by TESCl (36.8 uL, 0.219 mmol). The reaction mixture wasstirred at 0° C. for 30 minutes, and diluted with EtOAc (50 mL). Theorganic layer was washed and dried and concentrated in vacuo. Theresidue was chromatographed (40% ethyl acetate in hexanes) to afford 31mg (75%) of the desired product.

EXAMPLE 33 Preparation of 2′,7-TES-4-Cyclopentyl Ester Baccatin

A THF solution (0.6 mL) of the product of Example 32 (24.5 mg, 0.0324mmol) was treated at −40° C. with LHMDS (0.049 mL, 1 M, 0.049 mmol),followed by a THF solution (0.3 mL) of β-lactam of Example 23 (18.6 mg,0.049 mmol). The reaction was stirred at 0° C. for 1 hour, and thenquenched with NH₄Cl saturated solution. The reaction mixture wasextracted with EtOAc (35 mL), and washed, dried and concentrated invacuo. The residue was chromatographed (20-30-50% ethyl acetate inhexanes) to afford 15.5 mg (42%) of the desired product together with7.8 mg (31.8%) of the unreacted starting material.

EXAMPLE 34 Preparation of 4-Cyclopentyl Ester Paclitaxel

A acetonitrile solution (0.3 mL) of the product of Example 33 (13 mg,0.0115 mmol) was treated at 0° C. with pyridine (0.035 mL), followed by48% HF (0.103 mL). The reaction was kept at 5° C. overnight. Thereaction mixture was then diluted with EtOAc (30 mL), and washed with 1NHCl, NaHCO₃ and brine. The organic layer was dried and concentrated invacuo. The residue was chromatographed (50% ethyl acetate in hexanes) toafford 7.3 mg (70.3%) of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.17-8.14 (m, 2H), 7.74-7.26 (m, 13H), 6.90(d, J=8.9 Hz, 1H), 6.27 (s, 1H), 6.20 (m, 1H), 5.75 (d, J=8.9 Hz, 1H),5.69 (d, J=7.0 Hz, 1H), 4.79 (m, 2H), 4.44 (m, 1H), 4.24 (AB q, J=8.4Hz, 2H), 3.81 (d, J=7.0 Hz, 1H), 3.46 (d, J=4.7 Hz, 1H), 3.06 (m, 1H),2.56-1.15 (m, 27H, incl. singlets at 2.24, 1.82, 1.68, 1.33, 1.15, 3Heach). HRMS calcd. for C₅₁H₅₇NO₁₄Na (MNa⁺): 930.3677, found: 930.3714.

EXAMPLE 35 Preparation of 2′,7-silylated-4-Cyclopropane Taxane WithFuryl Side Chain

A THF solution (2 mL) of the product of Example 22 (75.8 mg, 0.104 mmol)was treated at −40° C. with LHMDS (0.136 mL, 1 M, 0.136 mmol) andβ-lactam* (57.3 mg, 0.156 mmol). The reaction was stirred at 0° C. for 1hour, and then quenched with NH₄Cl saturated solution (1 mL). Thereaction mixture was extracted with EtOAc, washed and dried andconcentrated in vacuo. The residue was chromatographed (20% ethylacetate in hexanes) to afford 113 mg (100%) of the desired product.

Methods for preparing the beta-lactam above are disclosed in U.S. Pat.No. 5,227,400.

EXAMPLE 36 Preparation of 4-Cyclopropyl Ester Taxane with Furyl SideChain

A acetonitrile solution of the product of Example 35 (2 mL) was treatedat 0° C. with pyridine (0.27 mL), followed by 48% HF (0.81 mL). Thereaction was kept at 5° C. for 3 hours, diluted with EtOAc (75 mL),washed with 1 N HCl, NaHCO₃ saturated solution, brine and dried andconcentrated in vacuo. The residue was chromatographed (50-60% ethylacetate in hexanes) to afford 68 mg (88.2%) of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.09-8.06 (m, 2H), 7.62-7.37 (m, 3H), 7.26 (s,1H), 6.37-6.30 (m, 3H), 6.19 (m, 1H), 5.65 (d, J=7.0 Hz, 1H), 5.37 (d,J=9.9 Hz, 1H), 5.23 (d, J=9.9 Hz, 1H), 4.82 (d, J=8.3 Hz, 1H), 4.76 (d,J=4.1 Hz, 1H), 4.42 (m, 1H), 4.18 (AB q, J=8.4 Hz, 2H), 3.85 (d, J=6.9Hz, 1H), 3.37 (d, J=5.4 Hz, 1H), 2.55-1.01 (m, 33H, incl. singlets at2.23, 1.90, 1.66, 1.26, 1.14, 3H each, 1.33, 9H).

HRMS calcd. for C₄₅H₅₆NO₁₆(MH⁺) 866.3599, found 866.3569.

EXAMPLE 37 Preparation of 2′,7-silylated-4-Cyclobutyl Ester Taxane withFuryl Side Chain

A THF solution (0.8 mL) of the product of Example 22 was treated at −40°C. with LHMDS (0.050 mL, 1 M, 0.50 mmol). After 2 minutes, β-lactam ofExample 35 (18.2 mg, 0.50 mmol) was added. The reaction mixture wasstirred at 0° C. for 1 hour, and quenched with NH₄Cl saturated solution.The reaction mixture was extracted and washed, dried and concentrated invacuo. The residue was chromatographed (20% ethyl acetate in hexanes) toafford 33.0 mg (89.4%) of the desired product.

EXAMPLE 38 Preparation of 4-Cyclobutyl Ester Taxane with Furyl SideChain

An acetonitrile solution (1 mL) of the product of Example 37 (30.0 mg,0.027 mmol) was treated at 0° C. with pyridine (0.081 mL), followed by48% HF (0.243 mL). The reaction was kept at 5° C. overnight, and dilutedwith EtOAc (50 mL), washed with 1 N HCl, NaHCO₃ saturated solution, andbrine. The organic layer was then dried and concentrated in vacuo. Theresidue was chromatographed (60% ethyl acetate in hexanes) to afford 22mg (92.4%) of the desired product.

¹H NMR (300 HMz, CDCl₃): δ8.13-8.10 (m, 2H), 7.62-7.45 (m, 3H),6.42-6.38 (m, 2H), 6.30 (s, 1H), 6.19 (m, 1H), 5.65 (d, J=7.1 Hz, 1H),5.34 (d, J=9.6 Hz, 1H), 5.18 (d, J=9.8 Hz, 1H), 4.90 (d, J=7.7 Hz, 1H),4.73 (dd, J=2.0 Hz, J′=5.7 Hz, 1H), 4.45 (m, 1H), 4.25 (AB q, J=8.4 Hz,2H), 3.80 (d, J=7.0 Hz, 1H), 3.50 (m, 1H), 3.27 (d, J=5.8 Hz, 1H),2.61-1.15 (m, 34H, incl. singlets at 2.24, 1.86, 1.68, 1.26, 1.15, 3Heach, 1.33, 9H).

EXAMPLE 39 Preparation of 7,13-TES-1- DMS-4-Butyrate Baccatin

The C4-hydroxyl baccatin derivative of Example 19 (181 mg, 0.218 mmol)was dissolved in dry THF (4.4 mL). This solution at 0° C. was treatedwith LHMDS (0.262 mL, 1 M, 0.262 mmol), after 30 minutes at thattemperature, butyryl chloride (0.034 mL, 0.33 mmol) was added. Thereaction was stirred at 0° C. for 1 hour and then quenched withsaturated NH₄Cl (3 mL). The reaction mixture was extracted with EtOAc(100 mL), and washed with water and brine. The organic layer was driedand concentrated in vacuo. The resulting residue was chromatographed(10% ethyl acetate in hexanes) to afford 138 mg (70.3%) of the desiredproduct.

EXAMPLE 40 Preparation of C4-Butyryl Ester Baccatin

7,13-TES-1-DMS-4-butyrate baccatin of Example 39 (527 mg, 0.586 mmol)was dissolved in dry acetonitrile (19.5 mL). To this solution at 0° C.was added pyridine (1.95 mL), followed by 48% HF solution (5.86 mL).After 30 minutes at 0° C., the reaction mixture was kept at 5° C.overnight. Then diluted with EtOAc (400 mL) and washed with 1 N Hcl,NaHCO3 saturated solution, brine and concentrated in vacuo. The residuewas chromatographed (60% ethyl acetate in hexanes) to afford 286 mg(80%) of the desired product.

EXAMPLE 41 Preparation of 7-TES-4-Butyrate Baccatin

4-butyrate baccatin of Example 40 (286 mg, 0.466 mmol) was dissolved indry DMF (2.3 mL). To this solution at 0° C. was added imidazole (127 mg,1.86 mmol), followed by TESCl (0313 mL, 1.86 mmol). The reaction wasstirred at 0° C. for 30 minutes and then diluted with EtOAc (100 mL).The reaction mixture was washed with water and brine and dried thenconcentrated in vacuo. The residue was chromatographed (30-50% ethylacetate in hexanes) to afford 283.3 mg (83.5%) of the desired product.

EXAMPLE 42 Preparation of 2′,7-BisTES-C4-Butyrate Paclitaxel

A THF (8.3 mL) solution of the product of Example 41 (300.6 mg, 0.413mmol) was cooled to −40° C. and treated with LHMDS (0.619 mL, 0.619mmol). After 5 minutes, a THF (4.1 mL) of β-lactam of Example 23 (236mg, 0.619 mmol) was added. The reaction was stirred at 0° C. for 1 hour,and then quenched with saturated NH₄Cl solution (3 mL). The reactionmixture was extracted with EtOAc (150 mL) and washed with water andbrine. The organic phase was dried and concentrated in vacuo, theresidue was chromatographed (20-30-60% ethyl acetate in hexanes) toafford 377 mg (82.3%) of the desired product.

EXAMPLE 43 Preparation of C-4-Butyrate Paclitaxel

An acetonitrile solution (15.3 mL) of the product of Example 42 (366 mg,0.334 mmol) was treated at 0° C. with pyridine (0.926 mL), followed by48% HF solution (2.78 mL). The reaction mixture was kept at 5° C.overnight and then diluted with EtOAc (200 mL), and washed with waterand brine. The organic layer was dried and concentrated in vacuo. Theresidue was chromatographed (60% ethyl acetate in hexanes) to afford 274mg (94.5%) of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.12-8.09 (m, 2H), 7.71-7.32 (m, 13H), 7.00(d, J=8.9 Hz, 1H), 6.25 (s, 1H), 6.16 (m, 1H), 5.73 (d, J=8.8 Hz, 1H),5.64 (d, J=7.0 Hz, 1H), 4.85 (d, KJ=9.4 Hz, 1H), 4.76 (m, 1H), 4.38 (m,1H), 4.20 (AB q, J=8.4 Hz, 2H), 3.77 (d, J=6.9 Hz, 1H), 3.70 (d, J=4.3Hz, 1H), 2.66-0.85 (m, 26H, incl. singlets at 2.20, 1.76, 1.65, 1.21,1.11, 3H each, triplet at 0.88, 3H).

EXAMPLE 44 Preparation of 7,13-TES-1-DMS-4-ethyl Carbonate Baccatin

A THF solution (5 mL) of the product of Example 19 (205 mg, 0.247 mmol)was treated at 0° C. with LHMDS (0.296 mL, 1 M, 0.296 mmol). After 30minutes at 0° C., ethyl chloroformate (0.0354 ml, 0.370 mmol) was added.The reaction was stirred at 0° C. for 1 hour and quenched with NH₄Clsaturated solution (3 mL). The reaction mixture was extracted with EtOAc(100 mL), washed with water and brine. The organic layer was dried andconcentrated in vacuo. The residue was chromatographed (10% ethylacetate in hexanes) to afford 155 mg (69.6%) of the desired product.

EXAMPLE 45 Preparation of C-4 Ethyl Carbonate Baccatin

To a acetonitrile solution (5.6 mL) of the product of Example 44 (152mg, 0.169 mmol) at 0° C. was added dry pyridine (0.56 mL), followed by48% HF (1.69 mL). After 30 minutes at 0° C., the reaction mixture waskept at 5° C. overnight. Then the residue was diluted with EtOAc (150mL), and washed with 1 N HCl and NaHCO₃ saturated solution. The organiclayer was then dried and concentrated in vacuo. The residue waschromatographed (60% ethyl acetate in hexanes to afford 99 mg (95.4%) ofthe desired product.

EXAMPLE 46 Preparation of 7-TES-C-4 Ethyl Carbonate Baccatin

4-ethyl carbonate baccatin of Example 45 (95 mg, 0.154 mmol) wasdissolved in dry DMF (0.771 mL). To this solution at 0° C. was addedimidazole (42 mg, 0.617 mmol) and TESCl (104 uL, 0.617 mmol). Thereaction mixture was diluted with EtOAc (100 mL) and washed with waterand brine. The organic layer was dried and concentrated in vacuo. Theresidue was chromatographed (40% ethyl acetate in hexanes) to afford 95mg (84.4%) of the desired product.

EXAMPLE 47 Preparation of 2′,7-TES-C-4 Ethyl Carbonate Paclitaxel

7-TES-4-ethyl carbonate baccatin of Example 46 (93.4 mg, 0.128 mmol) wasdissolved in THF (2.6 mL). This solution was cooled to −40° C. andtreated with LHMDS (0.192 mL, 1 M, 0.192 mmol), followed by a THFsolution (1.3 mL) of β-lactam of Example 23 (73.1 mg, 0192 mmol). Thereaction was kept at 0° C. for 1 hour and quenched with NH₄Cl (3 mL).The reaction mixture was extracted with EtOAc (100 mL), and washed withwater and brine. The organic layer was then dried and concentrated invacuo, the residue was chromatographed (20-30% ethyl acetate in hexanes)to afford 118 mg (83.0%) of the desired product.

EXAMPLE 48 Preparation of C-4 Ethyl Carbonate Paclitaxel

2′,7-TES-4-ethyl carbonate taxol of Example 47 (114 mg, 0.103 mmol) wasdissolved in acetonitrile (5.1 mL), to this solution at 0° C. was addedpyridine (0.285 mL), followed by 48% HF (0.855 mL). The reaction waskept at 5° C. overnight. The reaction was then diluted with EtOAc (100mL), washed with 1 N HCl, NaHCO₃ saturated solution and brine. Theorganic layer was dried and concentrated in vacuo. The residue waschromatographed (60% ethyl acetate in hexanes) to afford 75 mg (82.8%)of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.09-8.06 (m, 2H), 7.75-7.24 (m, 13H), 7.14(d, J=9.0 Hz, 1H), 6.24 (s, 1H), 6.10 (m, 1H), 5.79 (d, J=7.1 Hz, 1H),5.66 (d, J=6.9 Hz, 1H), 4.95 (d, J=8.2 Hz, 1H), 4.75 (m, 1H), 4.41-4.16(m, 5H), 3.89 (d, J=4.3 Hz, 1H), 3.81 (d, J=6.9 Hz, 1H), 2.56-1.11 (m,23H, incl. singlets at 2.21, 1.75, 1.65, 1.18, 1.11, 3H each, triplet at1.22, 3H).

EXAMPLE 49 Preparation of 2′,7-silylated-C-4-butyrate Taxane with FurylSide Chain

A THF solution (7.3 mL) of 7-silyl 4-butyrate baccatin of Example 41(266 mg, 0.365 mmol) was treated at −40° C. with LHMDS (0.548 mL, 1 M,0.548 mmol). After 2 minutes, a THF solution (3.6 ml) of β-lactam ofExample 35 (201 mg, 0.548 mmol) was added. The reaction mixture wasstirred at 0° C. for 1 hour, and quenched with NH₄Cl saturated solution.The reaction mixture was extracted and washed, dried and concentrated invacuo. The residue was chromatographed (20% ethyl acetate in hexanes) toafford 399.0 mg (99%) of the desired product.

EXAMPLE 50 Preparation of C-4 Butyrate Taxane with Furyl Side Chain

An acetonitrile solution (18.2 mL) of the product of Example 49 (399.0mg, 0.364 mmol) was treated at 0° C. with pyridine (1.01 mL), followedby 48% HF (3.03 mL). The reaction was kept at 5° C. overnight, anddiluted with EtOAc (200 mL), washed with 1 N HCl, NaHCO₃ saturatedsolution, and brine. The organic layer was then dried and concentratedin vacuo. The residue was chromatographed (60% ethyl acetate in hexanes)to afford 305 mg (96.5%) of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.05-8.02 (m, 2H), 7.56-7.35 (m, 4H),6.33-6.26 (m, 3H), 6.15 (m, 1H), 5.59 (d, J=7.0 Hz, 1H), 5.40 (d, J=9.7Hz, 1H), 5.26 (d, J=9.7 Hz, 1H), 4.85 (d, J=9.5 Hz, 1H), 4.66 (m, 1H),4.39 (m, 1H), 4.17 (AB q, J=8.4 Hz, 2H), 3.76 (d, J=6.9 Hz, 1H), 3.64(J=6.0 Hz, 1H), 2.65-0.91 (m, 35H, incl. singlets at 2.18, 1.82, 1.62,1.21, 1.09, 3H each, 1.28, 9H, triplet at 0.94, 3H).

EXAMPLE 51 Preparation of 7,13-BisTES-1-DMS-C-4 Methyl CarbonateBaccatin

The compound of Example 19 (118 mg, 0.150 mmol) was dissolved in THF (3mL). To this solution at 0° C. was added LHMDS (0.180 mL, 1M, 0.180mmol). After 30 minutes, methyl chloroformate (0.174 mL, 0.225 mmol) wasadded. After another 30 minutes, the reaction was quenched with NH4Cl.The reaction mixture was extracted with EtOAc (100 mL). The organiclayer was washed with water (10 mL×2) and brine (10 mL). The organicphase was then dried and concentrated in vacuo. The residue waschromatographed (5-10% EtOAc/Hexanes) to afford 104 mg (82.1%) of thedesired product.

EXAMPLE 52 Preparation of C-4 Methyl Carbonate Baccatin

The compound of Example 51 (89.0 mg, 0.105 mmol) was dissolved in CH3CN(3.5 mL). To this solution at 0° C. was added pyridine (0.30 mL),followed by 48% HF (1.05 mL). The reaction was stirred at 0° C. for 6hours, then diluted with EtOAc (100 mL). The reaction mixture was washedwith 1 N HCl (10 mL), NaHCO3 saturated solution (10 mL×3). The organicphase was dried and concentrated in vacuo. The residue waschromatographed (50% EtOAc/Hexanes) to afford 70 mg (100%) of thedesired product.

EXAMPLE 53 Preparation of 7-TES-C-4 Methyl Carbonate Baccatin

The compound of Example 52 (115.5 mg, 0.192 mmol) was dissolved in DMF(0.960 mL). To this solution at 0° C. was added imidazole (52.2 mg,0.767 mmol), followed by TESCl (0.128 mL, 0.767 mmol). After 30 minutes,the reaction mixture was diluted with EtOAc (100 mL). The organic layerwas washed with water (10 mL×2) and brine (10 mL). The organic phase wasthen dried and concentrated in vacuo. The residue was chromatographed(40% EtOAc/Hexanes) to afford 133 mg (96.8%) of the desired product.

EXAMPLE 54 Preparation of 2′,7-silylated-C-4-methyl Carbonate Taxanewith Furyl Side Chain

A THF solution (6.4 mL) of 7-silyl 4-methyl carbonate baccatin ofExample 53 (227.8 mg, 0.318 mmol) was treated at −40° C. with LHMDS(0.350 mL, 1 M, 0.350 mmol). After 2 minutes, a THF solution (3.6 ml) ofβ-lactam of Example 35 (140 mg, 0.382 mmol) was added. The reactionmixture was stirred at 0° C. for 1 hour, and quenched with NH₄Clsaturated solution. The reaction mixture was extracted and washed, driedand concentrated in vacuo. The residue was chromatographed (20% ethylacetate in hexanes) to afford 332.0 mg (96.3%) of the desired product.

EXAMPLE 55 Preparation of C-4-methyl Carbonate Taxane with Furyl SideChain

An acetonitrile solution (15.3 mL) of Example 54 (332.0 mg, 0.307 mmol)was treated at 0° C. with pyridine (1.7 mL), followed by 48% HF (5.1mL). The reaction was kept at 5° C. overnight, and diluted with EtOAc(200 mL), washed with 1 N HCl, NaHCO₃ saturated solution, and brine. Theorganic layer was then dried and concentrated in vacuo. The residue waschromatographed (60% ethyl acetate in hexanes) to afford 260 mg (99.0%)of the desired product.

¹H NMR (300 MHz, CDCl₃): δ8.05-8.02 (m, 2H), 7.53-7.37 (m, 4H),6.29-6.15 (m, 4H), 5.62 (d, J=6.9 Hz, 1H), 5.40 (d, J=9.6 Hz, 1H), 5.30(d, J=9.6 Hz, 1H), 4.91 (d, J=9.3 Hz, 1H), 4.68 (m, 1H), 4.34 (m, 1H),4.16 (AB q, J=8.5 Hz, 2H), 3.88 (s, 3H), 3.80 (d, J=8.9 Hz, 1H), 3.69(d, J=5.5 Hz, 1H), 2.63-1.08 (m, 28H, incl. singlets at 2.18, 1.85,1.60, 1.20, 1.08, 3H each, 1.26, 9H).

EXAMPLE 56 Preparation of 2′,7-silylated-C-4 Methyl Carbonate Paclitaxel

Compound of Example 53 (113.3 mg, 0.158 mmol) was dissolved in THF (3.16mL). To this solution at −40° C. was added LHMDS (0.237 mL, 1 M, 0.237mmol), followed by β-lactam of Example 23 (90.43 mg, 0.237 mmol). Followthe same procedure as above, 159 mg (91.6%) of the desired product wasobtained.

EXAMPLE 57 Preparation of C-4 Methyl Carbonate Paclitaxel

The compound of Example 56 (149 mg, 0.136 mmol) was dissolved in CH3CN(6.8 mL). To this solution at 0° C. was added pyridine (0.377 mL),followed by 48% HF (1.132 mL). Follow the same procedure as above, 103.4mg (87.6%) of the desired product was obtained.

EXAMPLE 58 Preparation of C-4 Cyclopropyl Ester-7-TES-13-oxayol-baccatin

To a suspension of the product of Example 22 (72 mg, 0.099 mmol) and theproduct of Example 6 (29.4 mg, 0.110 mmol) in toluene (2 mL) at roomtemperature was added DMAP (13.4 mg, 0.110). After 10 minutes, DCC (22.6mg, 0.110) was added. The reaction mixture was stirred at roomtemperature for 2 hours. The reaction mixture was then filtered throughCelite, rinsed with EtOAc. The organic layer was concentrated in vacuo.The residue was chromatographed (30% EtOAc/Hexanes) to afford desiredproduct (99 mg) in 100% yield.

¹H NMR (CDCl₃): δ8.27-8.24 (m, 2H), 8.03-7.26 (m, 13H), 6.42 (s, 1H),6.08 (m, 1H), 5.67 (d, J=7.0 Hz, 1H), 5.60 (d, J=6.0 Hz, 1H), 4.92 (d,J=6.1 Hz, 1H), 4.87 (d, J=8.3 Hz, 1H), 4.50 (dd, J=6.6 Hz, J′=10.3 Hz,1H), 4.16 (AB q, J=8.3 Hz, 2H), 3.85 (d, J=6.9 Hz, 1H), 2.56-0.52 (m,39H, incl. singlets at 2.15, 2.02, 1.68, 1.20, 1.18, 3H each, triplet at0.92, 9H).

HRMS calcd. for C₅₅H₆₆NO₁₃Si (MH⁺): 976.4303, found: 976.4271.

EXAMPLE 59 Preparation of C-4 Cyclopropyl Ester of Paclitaxel

To a solution of the product of Example 58 (83.4 mg, 0.084 mmol) in THF(0.8 mL) and methanol (0.8 mL) at 0° C. was added 1 N HCl (0.42 mL). Thereaction was kept at 4° C. for 14 hours. The reaction mixture was warmedto room temperature and NaHCO₃ saturated solution (2.1 mL) was added.The reaction was stirred at room temperature for 3 hours and then pouredinto H₂O, the reaction mixture was extracted with EtOAc (4×20 mL). Thecombined organic layer was dried and concentrated in vacuo. The residuewas chromatographed (60% EtOAc/hexanes) to afford desired product (45mg) in 60% yield.

EXAMPLE 60

In an oven-dried, argon purged 25 ml flask, BMS-189892-01 (485 mg, 3.0mmol) (Note 1) was dissolved in dry methanol (5.0 ml). To this flask wasadded trimethylsilyl chloride (326 mg, 3.0 mmol) dropwise via a syringeat 0° C. The reaction mixture was stirred at 0° C. for 5 minutes andthen the ice-water bath was removed. The reaction mixture was furtherstirred for 14 hours at room temperature. The reaction mixture wasconcentrated in vacuo and dried under high vacuum to yield 1quantitatively (691 mg, 100%) as a white foam.

1. Chem Abs.: 34408-064-33.

EXAMPLE 61

In a 25 ml flask 1 (691 mg, 3.0 mmol) from above was dissolved in sat.NaHCO₃ (10 ml). To this solution was added benzoyl chloroformate (512mg, 3.0 mmol) at room temperature. The reaction mixture was stirred for14 hours at room temperature during which time a white precipitateformed. The white precipitate was filtered off and washed with water(2×5 ml) and hexane 2×5 ml). The solid was dried under high vacuum togive 2 as an off white solid (745 mg, 86%).

EXAMPLE 62

In an oven-dried, argon purged 25 ml flask equipped with a Dean-Starktrap, 2 (745 mg, 2.58 mmol) was dissolved in toluene (12 ml) and DMF(2.5 ml). PPTS (502 mg, 2.0 mmol) was added to this solution. Thereaction mixture was heated to reflux with stirring for 28 hours. Themixture was diluted with ethyl acetated (50 ml) and was washed with H₂ 0(20 ml). The aqueous layer was extracted with ethyl acetate (50 ml). Thecombined organic fractions were dried over MgSO4, filtered, andconcentrated in vacuo to give crude 3 product (630 mg, 77%) as a darkoil. Crude 3 was purified by column chromatography (silica gel, 2×12 cm,10% ethyl acetate/hexane as eluant) to give 3 as a thick colorless oil(540 mg, 66%).

EXAMPLE 63

In a 25 ml flask, 3 (540 mg, 2.1 mmol) was dissolved in THF (6 ml) andH₂O (3 ml). To this solution was added solid LiOH (82 mg, 2.0 mmol) inone portion at room temperature. The resulting mixture was stirred for0.5 hour at room temperature. The reaction was quenched by adding HCl(2.4 ml of a 1.0 N solution) dropwise at room temperature. Next, themixture was poured into H₂O (10 ml), extracted with CH₂Cl₂ (4×15 ml),dried over MgSO₄, filtered and concentrated in vacuo to give crude 4(420 mg, 82%) as a yellow oil which was used directly in the next stepwithout further purification.

EXAMPLE 64

In an oven-dried, argon purged 25 ml flask, 4 (140 mg, 0.54 mmol),BMS-184260-01 (346 mg, 0.495 mmol) and N,N-dimethyl-aminopyridine (66mg, 0.54 mmol) were suspended in toluene (10 ml) at room temperature.After stirring the suspension for 20 minutes,1,3-dicyclohexylcarbodiimide (DCC) (111 mg, 0.54 mmol) was added in oneportion and the mixture was stirred at room temperature for 2 hours.Next, N,N-dimethylaminopyridine (66 mg, 0.54 mmol) and1,3-dicyclohexylcarbodiimide (DCC) (111 mg, 0.54 mmol) were added to thereaction mixture. The reaction mixture was stirred for 14 hours. Themixture was poured into sat. NH₄Cl (20 ml) and extracted with ethylacetate (100 ml). The organic extract was filtered through Celite, andthe Celite pad was then rinsed with ethyl acetate (4×50 ml). Thecombined organic layers were dried over MgSO₄, filtered and concentratedin vacuo to give crude 5 (582 mg, 125%). The crude product was purifiedby column chromatography (silica gel, 2×12 cm, 5% ethyl acetate/hexaneas eluant) to give 5 (413 mg, 89%) as a colorless oil.

EXAMPLE 65

In an oven-dried, argon purged 25 ml flask, 5 (92 mg, 0.094 mmol) wasdissolved in THF (2.0 ml) and methanol (2.0 ml). To this flask was addedaqueous HCl (0.5 ml of a 2.0 N solution) at 0° C. The solution was thenplaced in a 6° C. cold bath for 14 hours. The reaction mixture waswarmed to room temperature and to this flask was added saturated NaHCO₃(5.0 ml). The reaction mixture was stirred for 3 hours at roomtemperature. The mixture was poured into H2O (10 ml) and extracted withCH₂Cl₂ (4×20 ml). The combined organic fractions were dried over MgSO₄,filtered, and concentrated in vacuo to give crude product (70 mg) as awhite solid. To a hot solution of the crude product dissolved in CH₃OH(3.0 ml), H₂O (˜1.0 ml) was added till the solution became cloudy. Thesolution was cooled in a refrigerator over night. The white solid wasfiltered off using a medium fritted glass filter and dried under highvacuum to give end product (51 mg, 64%) as a white solid.

EXAMPLE 66 Preparation of C-4 Cyclopropyl Ester-7-TES Baccatin with aC-13(Oxayolyl-furyl)Side Chain

To a toluene (2.5 mL) suspension of the product of Example 22 (92.3 mg,0.127 mmol) and the product of Example 63 (36.0 mg, 0.140 mmol) at roomtemperature was added DMAP (17.1 mg, 0.140 mmol). After 10 minutes, DCC(28.8 mg, 0.140 mmol) was also added. After 2 hours at room temperature,second dose of reagents were added. The reaction was stirred overnightat room temperature. Then this reaction mixture was filtered and rinsedwith EtOAc. The organic layer was concentrated in vacuo. The residue waschromatographed (30% EtOAc/Hexanes) to afford desired product (125 mg)in 100% yield.

¹H NMR (CDCl₃): δ8.20-7.80 (m, 4H), 7.62-7.39 (m, 7H), 6.38 (m, 3H),6.08 (m, 1H), 5.67 (m, 2H), 5.20 (d, J=5.9 Hz, 1H), 5.20 (d, J=5.9 Hz,1H), 4.88 (d, J=9.2 Hz, 1H), 4.49 (dd, J=6.6 Hz, J′=10.2 Hz, 1H), 4.16(AB q, J=8.4 Hz, 2H), 3.86 (d, J=6.8 Hz, 1H), 2.54-0.52 (m, 39H, incl.singlets at 2.14, 2.03, 1.67, 1.21,1.15, 3H each, triplet at 0.91, 9H).

HRMS calcd. for C_(53 H) ₆₄NO₁₄Si (MH⁺): 966.4096, found: 966.4134.

EXAMPLE 67 Preparation of C-4 Cyclopropyl Ester Taxane with a Furyl SideChain

The compound of Example 66 (69 mg, 0.0715 mmol) was dissolved in THF(1.4 mL) and MeOH (1.4 mL). This solution was then treated at 0° C. with1 N HCl (0.716 mL). After 17 hours at 4° C., the reaction mixture waswarmed to room temperature and treated with NaHCO₃ saturated solution(6.5 mL). After 6 hours at room temperature, the reaction mixture wasextracted with EtOAc (4×20 mL). The combined organic layer was conc. invacuo. The residue was chromatographed (60% EtOAc/Hexanes) to afforddesired product (37.4 mg) in 60% yield.

¹H NMR (CDCl₃): δ8.12-8.09 (m, 2H), 7.74-7.26 (m, 7H), 6.85 (d, J=9.3Hz, 1H), 6.39 (s, 2H), 6.30 (s, 1H), 6.20 (m, 1H), 5.93 (d, J=9.3 Hz,1H), 5.67 (d, J=7.0 Hz, 1H), 4.88 (s, 1H), 4.82 (d, J=7.7 Hz, 1H), 4.42(m, 1H), 4.20 (AB q, J=8.5 Hz, 2H), 3.85 (d, J=6.8 Hz, 1H), 2.54-0.88(m, 24H, incl. singlets at 2.23, 1.88, 1.67, 1.24, 1.14, 3H each).

HRMS calcd. for C₄₇H₅₂NO₁₅ (MH⁺): 870.3337, found: 870.3307.

EXAMPLE 68 Preparation of C-4 Cyclopropyl Ester-2′ Ethyl Carbonate

A dichloromethane solution (22.8 mL) of the product of Example 24 (1.333g, 1.52 mmol) at 0° C. was added EtPr₂N (1.586 mL, 9.10 mmol), followedby EtOCOCl (0.87 mL, 9.10 mmol). The reaction was stirred at 0° C. for 6hours. Then the reaction mixture was diluted with EtOAc (200 mL), washedwith water (20 mL×3) and brine. The organic layer was dried andconcentrated in vacuo. The residue was chromatographed (50%EtOAc/Hexanes) to afford desired product (1.281 g) in 88.8% yieldtogether with 86 mg of the starting material (6.5%).

¹H NMR (CDCl₃): δ8.12-8.10 (m, 2H), 7.76-7.26 (m, 13H), 6.90 (d, J=9.4Hz, 1H), 6.27 (m, 2H), 6.01 (dd, J=2.1 Hz, J′=9.3 Hz, 1H), 5.68 (d,J=7.0 Hz, m 1H), 5.55 (d, J=2.4 Hz, 1H), 4.83 (d, J=8.2 Hz, 1H), 4.44(m, 1H), 4.23 (m, 4H), 3.83 (d, J=7.0 Hz, 1H), 2.53-0.87 (m, 27H, incl.singlets at 2.22, 1.95, 1.87, 1.67, 1.26, 3H each, triplet at 1.32, 3H).

HRMS calcd. for C₅₂H₅₈NO₁₆ (MH⁺): 952.3756, found: 952.3726.

EXAMPLE 69 Preparation of C-4 Cyclopropane-2′-ethyl Carbonate-7Substituted Precursor

The 2′ Ethyl carbonate of Example 68 (53 mg, 0.056 mmol) was dissolvedin DMSO (0.5 mL), Ac₂O (0.5 mL) was then added. The reaction was stirredat room temperature for 14 hours. The reaction mixture was diluted withEtOAc (50 mL), washed with water (5 mL×3), NaHCO3 saturated solution andbrine. The organic layer was then dried and concentrated in vacuo. Theresidue was chromatographed (40% EtOAc/Hexanes) to afford 56.3 mg of thedesired product in 100% yield.

¹H NMR (CDCl₃): δ8.10-8.07 (m, 2H), 7.76-7.26 (m, 13H), 6.90 (d, J=9.4Hz, 1H), 6.56 (s, 1H), 6.23 (m, 1H), 6.03 (d, J=9.5 Hz, 1H), 5.70 (d,J=6.9 Hz, 1H), 5.58 (d, J=2.1 Hz, 1H), 4.84 (d, J=8.9 Hz, 1H), 4.66 (s,2H), 4.21 (m, 5H), 3.91 (d, J=6.8 Hz, 1H), 2.80-0.87 (m, 30H, incl.singlets at 2.17, 2.12, 2.11, 1.75, 1.22, 1.20, 3H each, triplet at1.32, 3H).

EXAMPLE 70 Preparation of C-4 Cyclopropane-2′-ethylCarbonate-7-phosphate Precursor

To a dichloromethane solution (25.7 mL) of the product of Example 69(1.30 g, 1.286 mmol) was added 4A sieves (1.30 g), followed by a THFsolution (25.7 mL) of NIS (434 mg, 1.929 mmol) and dibenzyl phosphate(537 mg, 1.929 mmol). The reaction mixture was stirred at roomtemperature for 5 hours. Then the reaction mixture was filtered throughCelite and rinsed with EtOAc. The solvent was removed, and the residuewas dissolved in EtOAc (200 mL), washed with 1% NaHSO₃, brine, and driedover MgSO₄. The organic phase was concentrated in vacuo. The residue waschromatographed (50% EtOAc/Hexanes) to afford 1.278 g of product in80.1% yield.

¹H NMR (CDCl₃): δ8.10-8.07 (m, 2H), 7.76-7.26 (m, 23H), 6.90 (d, J=9.4Hz, 1H), 6.35 (s, 1H), 6.23 (m, 1H), 6.02 (d, J=9.5 Hz, 1H), 5.68 (d,J=6.8 Hz, 1H), 5.56 (s, 1H), 5.40 (m, 1H), 5.04 (m, 4H), 4.75 (d, J=9.0Hz, 1H), 4.20 (m, 5H), 3.89 (d, J=6.8 Hz, 1H), 2.78-0.86 (m, 27H, incl.singlets at 2.18, 1.99, 1.67, 1.18, 1.05, 3H each, triplet at 1.31, 3H).

EXAMPLE 71 Preparation of C-4 Cyclopropane-2′-ethylCarbonate-7-phosphate

Compound of Example 70 (1.278 g, 1.03 mmol) was dissolved in dry EtOAc(41.2 mL). To this solution was added catalyst Pd/C (438 mg, 10%, 0.412mmol). The reaction mixture was hydrogenated under 50 Psi for 12 hours.The reaction mixture was then filtered and concentrated in vacuo to give1.08 g of crude product in 100% yield.

The crude product was carried on for next step without furthercharacterization.

EXAMPLE 72 Preparation of C-4 Cyclopropane-2′-ethylCarbonate-7-phosphate Triethanolamine Salt

To a EtOAc solution (6.8 mL) of the product of Example 71 (1.08 g, 1.02mmol) was added a 0.100M solution of triethanolamine (6.8 mL. 0.15M) inEtOAc. The resulting mixture was placed in −20° C. overnight. Themixture was then filtered, the solid was washed with cooled 10%EtOAc/Hexane and dried under vacuum for 12 hours to afford the desiredprodrug (1.00 g) in 81.2% yield. The purity of the end product wasdetermined (by HPLC) to be >97% pure.

¹H NMR (CD₃OD): δ8.10-8.07 (m, 2H), 7.80-7.26 (m, 14H), 6.38 (s, 1H),6.07 (m,1H), 5.89 (d, J=5.2 Hz, 1H), 5.63 (d, J=7.0 Hz, 1H), 5.55 (d,J=5.2 Hz, 1H), 5.22 (m, 1H), 4.87 (m, 2H), 4.23 (m, 5H), 3.88 (d, J=7.0Hz, 1H), 3.80 (m, 6H), 3.30 (m, 1H), 3.18 (m, 6H), 2.97-0.86 (m, 26H,incl. singlets at 2.15, 1.94, 1.69, 1.57, 1.13, 3H each, triplet at1.30, 3H).

HRMS calcd. for C₅₃H₆₁NO₂₀P (MH⁺, M=acid): 1062.3525, found: 1062.3550.

EXAMPLE 73 Preparation of 7-TES-13-TMS Baccatin

7-TES baccatin of Example 10 (1.895 g, 2.707 mmol) was dissolved in dryDMF (10.8 mL). To this solution at 0° C. was added imidazole (736.4 mg,10.83 mmol), followed by TMSCl (1.37 mL, 10.83 mmol). The reaction wasstirred at 0° C. for 1.5 hours. The reaction mixture was then dilutedwith EtOAc (400 mL), and washed with water (20 mL×3), brine (15 mL). Theorganic layer was then dried and concentrated in vacuo. The residue waschromatographed (20% EtOAc/Hexanes) to afford 1.881 g (90%) of desiredproduct.

EXAMPLE 74 Preparation of 7-TES-13-TMS-1-DMS Baccatin

7-TES-13-TMS baccatin of Example 73 (305 mg, 0.430 mmol) was dissolvedin dry DMF (2 mL). To this solution at 0° C. was added imidazole (87.6mg, 1.289 mmol), followed by chlorodimethylsilane (122 mg, 1.289 mmol).After 1 hour, the reaction mixture was diluted with EtOAc (150 mL),washed with water (10 mL×3) and brine (10 mL). The resulting organiclayer was dried and concentrated in vacuo. The residue waschromatographed (10% EtOAc/Hexanes) to afford 305 mg (92.4%) of thedesired product.

EXAMPLE 75 Preparation of 7-TES-13-TMS-1-DMS-C-4 Hydroxy Baccatin

1-DMS-7-TES-13-TMS baccatin of Example 74 was dissolved in dry THF (8mL). To this solution at 0° C. was added Red-Al (0.314 mL, 60%, 1.61mmol). The mixture was stirred at 0° C. for 40 minutes, the reaction wasthen quenched with saturated solution of sodium tartrate (1 mL) for 2minutes. The reaction mixture was extracted with EtOAc (150 mL), washedwith water (15 mL×2) and brine (15 mL). The organic layer was dried andconcentrated in vacuo. The residue was chromatographed (10-20%EtOAc/Hexanes) to afford 143.8 mg (45.3%) of desired product.

NMR (300 MHz, CDCl₃): d 8.10-8.06 (m, 2H), 7.55-7.39 (m, 3H), 6.39 (s,1H), 5.59 (d, J=5.5 Hz, 1H), 4.68 (dd, J1=3.9 Hz, J2=9.6 Hz, 1H), 4.61(m, 1H), 4.53 (m, 1H), 4.21 (AB q, J=7.8 Hz, 2H), 4.03 (dd, J1=6.1 Hz,J2=11.6 Hz, 1H), 3.74 (s, 1H), 3.48 (d, J=5.7 Hz, 1H), 2.74-0.48 (m,34H, incl. singlets at 2.15, 2.06, 1.54, 1.16, 0.92, 3H each), 0.28 (s,9H), −0.015 & −0.32 (doublets, 3H each)

EXAMPLE 76 Preparation of 7-TES-13-TMS-1-DMS-C-4-[OC(O)CH═CH₂]Baccatin

The compound of Example 75 (99 mg, 0.125 mmol) was dissolved in dry THF(2.5 mL). To this solution at 0° C. was added LHMDS (0.150 mL, 1M, 0.150mmol). After 30 minutes, acryloyl chloride (0.0153 mL, 0.188 mmol) wasadded. After another 30 minutes, the reaction was quenched with NH4Clsaturated solution. The reaction mixture was extracted with EtOAc (100mL), and washed with water (10 mL×2) and brine (10 mL). The organicphase was dried and concentrated in vacuo. The residue waschromatographed (5-10% EtOAc/Hexanes) to afford 57.5 mg (54.6%) ofdesired product.

EXAMPLE 77 Preparation of C-4[OC(O)CH═CH₂]Baccatin

The compound of Example 76 (105 mg, 0.125 mmol) was dissolved in CH3CN(2.5 mL). To this solution at 0° C. was added pyridine (0.374 mL),followed by 48% HF (1.12 mL). The reaction was kept at 4° C. overnight.The reaction was then diluted with EtOAc (75 mL). The organic layer waswashed with 1 N HCl (5 mL), NaHCO3 saturated solution (5 mL×3) andbrine. The organic phase was then dried and concentrated in vacuo. Theresidue was chromatographed (60% EtOAc/Hexanes) to afford 60.6 mg(81.3%) of desired product.

EXAMPLE 78 Preparation of 7-TES-C-4[OC(O)CH═CH₂]Baccatin

The triol of Example 77 (60.0 mg, 0.100 mmol) was dissolved in dry DMF(0.66 mL). To this solution at 0° C. was added imidazole (27.2 mg, 0.400mmol), followed by TESCl (0.0672 mL, 0.400 mmol). After 30 minutes, thereaction was diluted with EtOAc (75 mL), washed with water (5 mL×3) andbrine. The organic layer was then dried and concentrated in vacuo. Theresidue was chromatographed (40% EtOAc/Hexanes) to afford 56.0 mg(78.4%) of desired product.

EXAMPLE 79 Preparation of 2′,7-Bis TES-4-[OC(O)CH═CH₂]Paclitaxel

The baccatin of Example 78 (50 mg, 0.0702 mmol) was dissolved in THF(1.4 mL). To this solution at −40° C. was added LHMDS (0.0843 mL, 1M,0.0843 mmol), followed immediately by a THF (0.7 mL) solution ofβ-lactam of Example 23 (40.1 mg, 0.105 mmol). After 2 minutes at −40°C., the reaction was stirred at 0° C. for 1 hour. The reaction was thenquenched with NH4Cl saturated solution. The reaction mixture wasextracted with EtOAc, and washed water. The organic layer was dried andconcentrated in vacuo. The residue was chromatographed (20-30%EtOAc/Hexanes) to afford 66 mg (86%) of the desired product.

EXAMPLE 80 Preparation of C-4[OC(O)CH═CH₂]Paclitaxel

The compound of Example 79 (46 mg, 0.0421 mmol) was dissolved in CH3CN(0.85 mL). To this solution at 0° C. was added pyridine (0.125 mL),followed by 48% HF (0.375 mL). The reaction was kept at 4° C. overnight.The reaction mixture was then diluted with EtOAc (40 mL), washed with 1N HCl (3 mL), NaHCO3 saturated solution (3 mL×3). The organic layer wasdried and concentrated in vacuo. The residue was chromatographed (70%EtOAc/Hexanes) to afford 28 mg (76.9%) of the desired product.

EXAMPLE 81 Preparation of 7,13-Bis-TES-1-DMS-C-4-[C(O)C₆H₅]Baccatin

The compound of Example 19 (279 mg, 0.336 mmol) was dissolved in dry THF(7 mL). To this solution at 0° C. was added LHMDS (0.403 mL, 1M, 0.403mmol). After 30 minutes, benzoyl chloride (0.0585 mL, 0.504 mmol) wasadded. After 30 minutes, the reaction was quenched with NH4Cl saturatedsolution. The reaction mixture was extracted with EtOAc (150 mL). Theorganic layer was washed with water and brine and dried and concentratedin vacuo. The residue was chromatographed (10% EtOAc/Hexanes) to afford215.5 mg (68.6%) of the desired product.

EXAMPLE 82 Preparation of C-4-Benzoyl Baccatin

The compound of Example 81 (161 mg, 0.172 mmol) was dissolved in CH3CN.To this solution at 0° C. was added pyridine (0.57 mL), followed by 48%HF (1.80 mL). After 5 hours at 4° C., another dose of reagent was added.The reaction was kept at 4° C. overnight. The reaction mixture was thendiluted with EtOAc (100 mL), and washed with 1N HCl (5 mL), NaHCO3 (5mL×3). The organic phase was dried and concentrated in vacuo. Theresidue thus obtained was chromatographed (30-50% EtOAc/Hexanes) toafford 48 mg (43.0%) of the desired end product.

EXAMPLE 83 Preparation of 7-TES-C-4-Benzoyl Baccatin

The triol of Example 82 (48.0 mg, 0.074 mmol) was dissolved in DMF (0.40mL). To this solution at 0° C., was added imidazole (20.1 mg, 0.296mmol), followed by TESCl (0.0496 mL, 0.296 mmol). After 30 minutes, thereaction mixture was diluted with EtOAc (45 mL), and washed with water(1 mL×3) and brine. The organic phase was dried and concentrated invacuo. The residue was chromatographed (40% EtOAc/Hexanes) to afford 48mg (85.0%) of the desired end product.

EXAMPLE 84 Preparation of C-4-Benzoyl Paclitaxel

The compound of Example 83 (364.6 mg, 0.478 mmol) was dissolved in THF(9.6 mL). To this solution at −40° C. was added LHMDS (0.718 mL, 1M,0.718 mmol), followed by β-lactam of Example 23 (273.5 mg, 0.718 mmol).Following the same procedure as in previous examples, 415 mg (75.9%) ofcompound was obtained. Thereafter the deprotected paclitaxel analoguemay be obtained by dissolving the above compound in CH₃CN (16.5 mL) andat 0° C. adding pyridine (0.36 mL) followed by 48% HF (3.0 mL).Following the steps outlined in Example 80, the paclitaxel analogue isobtained in 315 mg (94.8%) yield.

EXAMPLE 85 Preparation of 4-Cyclobutane Taxane with Furyl Side Chain

7-TES-4-cyclobutyl baccatin of Example 27 (154 mg, 0.208 mmol) wasdissolved in dry toluene (4 mL). To this solution at room temperaturewas added free acid of Example 63 (64.2 mg, 0.250 mmol) and DMAP (30.5mg, 0.250 mmol). After 10 minutes, DCC (51.4 mg, 0.250 mmol) was added.The reaction was stirred for 2 hours, and at this time another dose ofDCC/DMAP was added. The reaction was further stirred for 12 hours. Thereaction mixture was then filtered through Celite, and the “cake” wasrinsed with EtOAc. The combined organic layer was concentrated in vacuo,and the residue was chromatographed (30-40% ethyl acetate in hexanes) toafford 222 mg (100%) of the desired product.

A THF (2 mL) and MeOH (2 mL) solution of (A) (182 mg, 0.186 mmol) wastreated at 0° C. with 1 N HCl (1.86 mL). After 1 hour at 0° C., thereaction was kept at 4° C. overnight. The reaction mixture was thentreated with saturated NaHCO₃ (9.6 mL). After 5 hours at roomtemperature, the reaction mixture was diluted with EtOAc (120 mL), andwashed with water (4×10 mL). The organic layer was then dried withMgSO₄, and concentrated in vacuo. The residue was chromatographed(40-60% ethyl acetate in hexanes) to afford 77 mg (47%) of the desiredproduct.

¹H NMR (CDCl₃): 8.15-8.12 (m, 2H), 7.73-7.35 (m, 9H), 6.87 (d, J=9.2 Hz,1H), 6.44 (m, 2H), 6.28 (s, 1H), 6.20 (m,1H), 5.89 (d, J=9.2 Hz, 1H),5.66 (d, J=7.1 Hz, 1H), 4.90 (d, J=8.1 Hz, 1H), 4.85 (s, 1H), 4.44 (m,1H), 4.27 (AB q, J=8.4 Hz, 2H), 3.80 (d, J=7.0 Hz, 1H), 3.56 (m, 1H),2.61-0.92 (m, 25H, incl. singlets at 2.22, 1.83, 1.69, 1.23, 1.13 3Heach). ¹³C NMR (CDCl₃): 203.6, 174.4, 172.4, 171.2, 166.9, 166.8, 150.9,142.5, 142.0, 133.5, 133.3, 132.9, 131.9, 130.1, 130.0, 129.7, 129.0,128.5, 127.0, 110.8, 108.0, 84.6, 80.8, 78.9, 76.4, 75.4 75.0, 72.5,72.0, 71.3, 58.5, 50.1, 45.6, 43.1, 38.8, 35.6, 35.5, 26.7, 25.3, 25.1,21.9, 20.7, 18.2, 14.6, 9.5.

HRMS calcd. for C₄₈H₅₄NO₁₅ (MH⁺): 884.3493, found: 884.3472.

EXAMPLE 86 Preparation of Paclitaxel

The compound of Example 10(b) was added to a 5 ml flask and dissolved inTHF. Methanol was added and the slightly yellowish homogeneous solutionwas cooled to 0° C. HCl was added and the resulting homogeneous solutionwas stirred at 0° C. for ½ hour and then transferred to a 4° C. coldroom. After 19 ½ hours from the addition of HCl, TLC showed no startingmaterial. The reaction solution was added to a flask containing 20 ml of{fraction (1/2 )}saturated solution of NaCl. The resulting heterogeneousmixture was stirred at room temperature for 45 minutes. The mixture wasfiltered and the solid was washed with 15 ml of H₂O and air-dried on thefritted funnel. The white solid was then washed through the frit bydissolution in THF into another flask and concentrated to give 0.169 gr.of a glassy solid. The material was transferred to a vial and dissolvedin 1.0 ml of THF. NEt₃ (4 eq.; 0.63 mmoles; 88 ml) was added, aprecipitate formed. The heterogeneous mixture was stirred at roomtemperature. TLC showed the reaction to be essentially complete after4.25 hours after the addition of NEt₃. The mixture was diluted with 5 mlEtOAc and 5 ml of H₂O and shaken. The layers were separated. The aqueousfraction was extracted twice with 5 ml EtOAc. The combined organicfractions were washed with 5 ml of HCl (in), 5 ml of saturated aqueousNaCl, dried over Na₂SO₄, filtered and concentrated to give 0.127 gr. ofa white solid (paclitaxel) in 93.9% yield.

What is claimed is:
 1. A compound of the formula:

wherein R¹ is alkyl, aryl or alkoxy; R³ is alkyl, aryl or heterocyclo; R⁴ is hydrogen; and T is

 wherein R⁸ is hydroxyl or alkylcarbonyloxy; R⁹ is hydroxyl or a protected hydroxyl group; R¹⁰ is cycloalkyl or R¹⁶—O—; R¹¹ is aryl; and R¹⁶ is lower alkyl.
 2. The compound of claim 1, wherein R¹ is phenyl or t-butyloxy; R³ is phenyl, 2- or 3- thienyl, 2- or 3- furanyl, isobutenyl, 2-propenyl, or (CH₃)₂CH—; R⁸ is hydroxyl or acetyloxy; R⁹ is hydroxyl or trialkysilyloxy; R¹⁰ is cycloalkyl selected from cyclopropyl, cyclobutyl, or cyclopentyl; and R¹¹ is phenyl.
 3. The compound of claim 2, wherein R¹⁰ is cyclopropyl or cyclobutyl.
 4. The compound of claim 3 wherein R¹⁰ is cyclopropyl.
 5. A compound of the formula

wherein R¹⁰ is selected from the group consisting of cyclopropyl, cyclobutyl, and cyclopentyl.
 6. A compound of the formula

wherein R¹⁰ is —OMe.
 7. A method for the preparation of a sidechain-bearing taxane of the formula IV or a salt thereof:

wherein R¹ is R⁵, R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N—; R³ and R⁴ are independently R⁵, R⁵—O—C(O)—, or(R⁵)(R⁶)N—C(O)—; R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo; R⁷ is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo; and T is

 wherein R⁸ is hydrogen, hydroxyl, R¹⁴—O—, R¹⁵—C(O)—O—, or R¹⁵—O—C(O)—O—; R⁹ is hydrogen, hydroxyl, fluoro, R¹⁴—O, R¹⁵—C(O)—O—, or R¹⁵—O—C(O)—O—; R¹⁰ and R¹¹ are independently hydrogen, alkyl, R¹⁶—O—, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo; R¹⁴ is a hydroxyl protecting group; R¹⁵ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo; and R¹⁶ is lower alkyl; with the proviso that R¹⁰ is not methyl comprising the step of reacting a sidechain- bearing taxane of the formula X or a salt thereof:

 with a base to form said sidechain-bearing taxane of the formula IV or salt thereof.
 8. The method of claim 1, wherein said base is an alkali metal bicarbonate.
 9. The method of claim 1, wherein taxol or taxotere is prepared as said compound of the formula IV.
 10. The method of claim 1, wherein said sidechain-bearing taxane of the formula X or salt thereof is prepared by a method comprising the step of reacting an oxazoline sidechain-bearing taxane of formula III or salt thereof:

with an aqueous acid capable of opening the ring of the oxazoline group of said taxane of the formula III or salt thereof to form said compound of the formula X or salt thereof.
 11. The method of claim 10, wherein said oxazoline sidechain-bearing taxane of the formula III or a salt thereof is prepared by a method comprising the step of reacting an oxazoline of formula II or a salt thereof:

with a taxane having a hydroxyl group bonded directly to C-13 thereof, or a salt thereof, in the presence of a coupling agent selected from the group consisting of dicyclohexylcarbodiimide, 1,3-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride, bis(2-oxo3-oxazolidinyl)-phosphonic chloride, carbonyl diimidazole, pivaloyl chloride, 2,4,6-trichlorobenzoyl chloride; 1-hydroxbenzotriazole, N-hydroxysuccinimide; triethylamine, pyridine, and combinations thereof, to form said sidechain-bearing taxane of the formula III or salt thereof.
 12. The method of claim 11, wherein said oxazoline compound of the formula II or salt thereof is prepared by a method comprising the step of converting the group —C(O)—R² of an oxazoline of formula I or salt thereof to a carboxyl group:

wherein R² is R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N—.
 13. The method of claim 12, wherein said oxazoline compound of the formula I or salt thereof is prepared by a method comprising the step of reacting a compound of formula V or salt thereof:

in the presence of a base with an activating agent selected from the group consisting of sulfonyl halides, phosphorous oxychloride, phosphorus pentachloride, and thionyl chloride, to allow intramolecular displacement and formation of said compound of the formula I or salt thereof.
 14. The method of claim 12, wherein said oxazoline compound of the formula I or salt thereof is prepared by a method comprising the step of reacting a compound of formula V or a salt thereof:

with an acid capable of effecting dehydration of the compound of formula V or salt thereof to form said compound of the formula I or salt thereof.
 15. The method of claim 12, wherein said oxazoline compound of the formula I or salt thereof wherein R¹ is R^(1′), and R^(1′) is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo, is prepared by a method comprising the step of reacting a compound of the formula VII or a salt thereof:

with a compound of formula VIII or a salt thereof:

wherein E is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or heterocyclo.
 16. The method of claim 7, wherein said sidechain-bearing taxane of the formula X or salt thereof is prepared by a method comprising: (a) hydrolyzing an oxazoline of formula I or salt thereof:

 wherein R² is R⁷—O—, R⁷—S—, or (R⁵)(R⁶)N— to an oxazoline of formula II or a salt thereof:

(b) reacting the oxazoline of formula II or salt thereof with a taxane having a hydroxyl group directly bonded to C13 thereof, or a salt thereof, in the presence of a coupling agent selected from the group consisting of dicyclohexylcarbodiimide, 1,3-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride, bis(2-oxo-3-oxazolidinyl)-phosphonic chloride, carbonyl diimidazole, pivaloyl chloride, 2,4,6-trichlorobenzoyl chloride; 1-hydroxbenzotriazole, N-hydroxysuccinimide; triethylamine, pyridine, and combinations thereof, to form an oxazoline sidechain-bearing taxane of formula III or a salt thereof;

(c) reacting the oxazoline sidechain-bearing taxane of formula III or salt thereof with an aqueous acid capable of opening the oxazoline ring of said compound of the formula III or salt thereof to form said sidechain-bearing taxane of formula X or salt thereof. 